Don't look for headers and libraries in "traditional" locations.

Patch from Nixpkgs by Eelco Dolstra <eelco.dolstra@logicblox.com>.

diff -ru -x '*~' -x '*.rej' perl-5.20.0-orig/Configure perl-5.20.0/Configure
--- perl-5.20.0-orig/Configure	2014-05-26 15:34:18.000000000 +0200
+++ perl-5.20.0/Configure	2014-06-25 10:43:35.368285986 +0200
@@ -106,15 +106,7 @@
 fi
 
 : Proper PATH setting
-paths='/bin /usr/bin /usr/local/bin /usr/ucb /usr/local /usr/lbin'
-paths="$paths /opt/bin /opt/local/bin /opt/local /opt/lbin"
-paths="$paths /usr/5bin /etc /usr/gnu/bin /usr/new /usr/new/bin /usr/nbin"
-paths="$paths /opt/gnu/bin /opt/new /opt/new/bin /opt/nbin"
-paths="$paths /sys5.3/bin /sys5.3/usr/bin /bsd4.3/bin /bsd4.3/usr/ucb"
-paths="$paths /bsd4.3/usr/bin /usr/bsd /bsd43/bin /opt/ansic/bin /usr/ccs/bin"
-paths="$paths /etc /usr/lib /usr/ucblib /lib /usr/ccs/lib"
-paths="$paths /sbin /usr/sbin /usr/libexec"
-paths="$paths /system/gnu_library/bin"
+paths=''
 
 for p in $paths
 do
@@ -1337,8 +1329,7 @@
 archname=''
 : Possible local include directories to search.
 : Set locincpth to "" in a hint file to defeat local include searches.
-locincpth="/usr/local/include /opt/local/include /usr/gnu/include"
-locincpth="$locincpth /opt/gnu/include /usr/GNU/include /opt/GNU/include"
+locincpth=""
 :
 : no include file wanted by default
 inclwanted=''
@@ -1349,17 +1340,12 @@
 
 libnames=''
 : change the next line if compiling for Xenix/286 on Xenix/386
-xlibpth='/usr/lib/386 /lib/386'
+xlibpth=''
 : Possible local library directories to search.
-loclibpth="/usr/local/lib /opt/local/lib /usr/gnu/lib"
-loclibpth="$loclibpth /opt/gnu/lib /usr/GNU/lib /opt/GNU/lib"
+loclibpth=""
 
 : general looking path for locating libraries
-glibpth="/lib /usr/lib $xlibpth"
-glibpth="$glibpth /usr/ccs/lib /usr/ucblib /usr/local/lib"
-test -f /usr/shlib/libc.so && glibpth="/usr/shlib $glibpth"
-test -f /shlib/libc.so     && glibpth="/shlib $glibpth"
-test -d /usr/lib64         && glibpth="$glibpth /lib64 /usr/lib64 /usr/local/lib64"
+glibpth=""
 
 : Private path used by Configure to find libraries.  Its value
 : is prepended to libpth. This variable takes care of special
@@ -1391,8 +1377,6 @@
 libswanted="$libswanted m crypt sec util c cposix posix ucb bsd BSD"
 : We probably want to search /usr/shlib before most other libraries.
 : This is only used by the lib/ExtUtils/MakeMaker.pm routine extliblist.
-glibpth=`echo " $glibpth " | sed -e 's! /usr/shlib ! !'`
-glibpth="/usr/shlib $glibpth"
 : Do not use vfork unless overridden by a hint file.
 usevfork=false
 
@@ -2446,7 +2430,6 @@
 zip
 "
 pth=`echo $PATH | sed -e "s/$p_/ /g"`
-pth="$pth $sysroot/lib $sysroot/usr/lib"
 for file in $loclist; do
 	eval xxx=\$$file
 	case "$xxx" in
@@ -4936,7 +4919,7 @@
 : Set private lib path
 case "$plibpth" in
 '') if ./mips; then
-	plibpth="$incpath/usr/lib $sysroot/usr/local/lib $sysroot/usr/ccs/lib"
+	plibpth="$incpath/usr/lib"
     fi;;
 esac
 case "$libpth" in
@@ -8600,13 +8583,8 @@
 echo " "
 case "$sysman" in
 '')
-	syspath='/usr/share/man/man1 /usr/man/man1'
-	syspath="$syspath /usr/man/mann /usr/man/manl /usr/man/local/man1"
-	syspath="$syspath /usr/man/u_man/man1"
-	syspath="$syspath /usr/catman/u_man/man1 /usr/man/l_man/man1"
-	syspath="$syspath /usr/local/man/u_man/man1 /usr/local/man/l_man/man1"
-	syspath="$syspath /usr/man/man.L /local/man/man1 /usr/local/man/man1"
-	sysman=`./loc . /usr/man/man1 $syspath`
+	syspath=''
+	sysman=''
 	;;
 esac
 if $test -d "$sysman"; then
@@ -19900,9 +19878,10 @@
 case "$full_ar" in
 '') full_ar=$ar ;;
 esac
+full_ar=ar
 
 : Store the full pathname to the sed program for use in the C program
-full_sed=$sed
+full_sed=sed
 
 : see what type gids are declared as in the kernel
 echo " "
Only in perl-5.20.0/: Configure.orig
diff -ru -x '*~' -x '*.rej' perl-5.20.0-orig/ext/Errno/Errno_pm.PL perl-5.20.0/ext/Errno/Errno_pm.PL
--- perl-5.20.0-orig/ext/Errno/Errno_pm.PL	2014-05-26 15:34:20.000000000 +0200
+++ perl-5.20.0/ext/Errno/Errno_pm.PL	2014-06-25 10:31:24.317970047 +0200
@@ -126,11 +126,7 @@
 	if ($dep =~ /(\S+errno\.h)/) {
 	     $file{$1} = 1;
 	}
-    } elsif ($^O eq 'linux' &&
-	      $Config{gccversion} ne '' && 
-	      $Config{gccversion} !~ /intel/i
-	      # might be using, say, Intel's icc
-	     ) {
+    } elsif (0) {
     # When cross-compiling we may store a path for gcc's "sysroot" option:
     my $sysroot = $Config{sysroot} || '';
 	# Some Linuxes have weird errno.hs which generate
Only in perl-5.20.0/ext/Errno: Errno_pm.PL.orig
diff -ru -x '*~' -x '*.rej' perl-5.20.0-orig/hints/freebsd.sh perl-5.20.0/hints/freebsd.sh
--- perl-5.20.0-orig/hints/freebsd.sh	2014-01-31 22:55:51.000000000 +0100
+++ perl-5.20.0/hints/freebsd.sh	2014-06-25 10:25:53.263964680 +0200
@@ -119,21 +119,21 @@
         objformat=`/usr/bin/objformat`
         if [ x$objformat = xaout ]; then
             if [ -e /usr/lib/aout ]; then
-                libpth="/usr/lib/aout /usr/local/lib /usr/lib"
-                glibpth="/usr/lib/aout /usr/local/lib /usr/lib"
+                libpth=""
+                glibpth=""
             fi
             lddlflags='-Bshareable'
         else
-            libpth="/usr/lib /usr/local/lib"
-            glibpth="/usr/lib /usr/local/lib"
+            libpth=""
+            glibpth=""
             ldflags="-Wl,-E "
             lddlflags="-shared "
         fi
         cccdlflags='-DPIC -fPIC'
         ;;
 *)
-       libpth="/usr/lib /usr/local/lib"
-       glibpth="/usr/lib /usr/local/lib"
+       libpth=""
+       glibpth=""
        ldflags="-Wl,-E "
         lddlflags="-shared "
         cccdlflags='-DPIC -fPIC'
diff -ru -x '*~' -x '*.rej' perl-5.20.0-orig/hints/linux.sh perl-5.20.0/hints/linux.sh
--- perl-5.20.0-orig/hints/linux.sh	2014-05-26 15:34:20.000000000 +0200
+++ perl-5.20.0/hints/linux.sh	2014-06-25 10:33:47.354883843 +0200
@@ -150,25 +150,6 @@
     ;;
 esac
 
-# Ubuntu 11.04 (and later, presumably) doesn't keep most libraries
-# (such as -lm) in /lib or /usr/lib.  So we have to ask gcc to tell us
-# where to look.  We don't want gcc's own libraries, however, so we
-# filter those out.
-# This could be conditional on Unbuntu, but other distributions may
-# follow suit, and this scheme seems to work even on rather old gcc's.
-# This unconditionally uses gcc because even if the user is using another
-# compiler, we still need to find the math library and friends, and I don't
-# know how other compilers will cope with that situation.
-# Morever, if the user has their own gcc earlier in $PATH than the system gcc,
-# we don't want its libraries. So we try to prefer the system gcc
-# Still, as an escape hatch, allow Configure command line overrides to
-# plibpth to bypass this check.
-if [ -x /usr/bin/gcc ] ; then
-    gcc=/usr/bin/gcc
-else
-    gcc=gcc
-fi
-
 case "$plibpth" in
 '') plibpth=`LANG=C LC_ALL=C $gcc $ccflags $ldflags -print-search-dirs | grep libraries |
 	cut -f2- -d= | tr ':' $trnl | grep -v 'gcc' | sed -e 's:/$::'`
@@ -178,32 +159,6 @@
     ;;
 esac
 
-case "$libc" in
-'')
-# If you have glibc, then report the version for ./myconfig bug reporting.
-# (Configure doesn't need to know the specific version since it just uses
-# gcc to load the library for all tests.)
-# We don't use __GLIBC__ and  __GLIBC_MINOR__ because they
-# are insufficiently precise to distinguish things like
-# libc-2.0.6 and libc-2.0.7.
-    for p in $plibpth
-    do
-        for trylib in libc.so.6 libc.so
-        do
-            if $test -e $p/$trylib; then
-                libc=`ls -l $p/$trylib | awk '{print $NF}'`
-                if $test "X$libc" != X; then
-                    break
-                fi
-            fi
-        done
-        if $test "X$libc" != X; then
-            break
-        fi
-    done
-    ;;
-esac
-
 # Are we using ELF?  Thanks to Kenneth Albanowski <kjahds@kjahds.com>
 # for this test.
 cat >try.c <<'EOM'
@@ -367,33 +322,6 @@
 	;;
 esac
 
-# SuSE8.2 has /usr/lib/libndbm* which are ld scripts rather than
-# true libraries. The scripts cause binding against static
-# version of -lgdbm which is a bad idea. So if we have 'nm'
-# make sure it can read the file
-# NI-S 2003/08/07
-case "$nm" in
-    '') ;;
-    *)
-    for p in $plibpth
-    do
-        if $test -r $p/libndbm.so; then
-            if $nm $p/libndbm.so >/dev/null 2>&1 ; then
-                echo 'Your shared -lndbm seems to be a real library.'
-                _libndbm_real=1
-                break
-            fi
-        fi
-    done
-    if $test "X$_libndbm_real" = X; then
-        echo 'Your shared -lndbm is not a real library.'
-        set `echo X "$libswanted "| sed -e 's/ ndbm / /'`
-        shift
-        libswanted="$*"
-    fi
-    ;;
-esac
-
 # Linux on Synology.
 if [ -f /etc/synoinfo.conf -a -d /usr/syno ]; then
     # Tested on Synology DS213 and DS413