Install nss.pc and nss-config.
Based on nss-3.17-gentoo-fixups.patch from nixpkgs.

--- nss-3.17.1/nss/config/Makefile
+++ nss-3.17.1/nss/config/Makefile
@@ -0,0 +1,40 @@
+CORE_DEPTH = ..
+DEPTH      = ..
+
+include $(CORE_DEPTH)/coreconf/config.mk
+
+NSS_MAJOR_VERSION = `grep "NSS_VMAJOR" ../lib/nss/nss.h | awk '{print $$3}'`
+NSS_MINOR_VERSION = `grep "NSS_VMINOR" ../lib/nss/nss.h | awk '{print $$3}'`
+NSS_PATCH_VERSION = `grep "NSS_VPATCH" ../lib/nss/nss.h | awk '{print $$3}'`
+PREFIX = /usr
+
+all: export libs
+
+export:
+	# Create the nss.pc file
+	mkdir -p $(DIST)/lib/pkgconfig
+	sed -e "s,@prefix@,$(PREFIX)," \
+	    -e "s,@exec_prefix@,\$${prefix}," \
+	    -e "s,@libdir@,\$${prefix}/lib/nss," \
+	    -e "s,@includedir@,\$${prefix}/include/nss," \
+	    -e "s,@NSS_MAJOR_VERSION@,$(NSS_MAJOR_VERSION),g" \
+	    -e "s,@NSS_MINOR_VERSION@,$(NSS_MINOR_VERSION)," \
+	    -e "s,@NSS_PATCH_VERSION@,$(NSS_PATCH_VERSION)," \
+	    nss.pc.in > nss.pc
+	chmod 0644 nss.pc
+	cp nss.pc $(DIST)/lib/pkgconfig
+
+	# Create the nss-config script
+	mkdir -p $(DIST)/bin
+	sed -e "s,@prefix@,$(PREFIX)," \
+	    -e "s,@NSS_MAJOR_VERSION@,$(NSS_MAJOR_VERSION)," \
+	    -e "s,@NSS_MINOR_VERSION@,$(NSS_MINOR_VERSION)," \
+	    -e "s,@NSS_PATCH_VERSION@,$(NSS_PATCH_VERSION)," \
+	    nss-config.in > nss-config
+	chmod 0755 nss-config
+	cp nss-config $(DIST)/bin
+
+libs:
+
+dummy: all export libs
+
--- nss-3.17.1/nss/config/nss-config.in
+++ nss-3.17.1/nss/config/nss-config.in
@@ -0,0 +1,145 @@
+#!/bin/sh
+
+prefix=@prefix@
+
+major_version=@NSS_MAJOR_VERSION@
+minor_version=@NSS_MINOR_VERSION@
+patch_version=@NSS_PATCH_VERSION@
+
+usage()
+{
+	cat <<EOF
+Usage: nss-config [OPTIONS] [LIBRARIES]
+Options:
+	[--prefix[=DIR]]
+	[--exec-prefix[=DIR]]
+	[--includedir[=DIR]]
+	[--libdir[=DIR]]
+	[--version]
+	[--libs]
+	[--cflags]
+Dynamic Libraries:
+	nss
+	ssl
+	smime
+	nssutil
+EOF
+	exit $1
+}
+
+if test $# -eq 0; then
+	usage 1 1>&2
+fi
+
+lib_ssl=yes
+lib_smime=yes
+lib_nss=yes
+lib_nssutil=yes
+
+while test $# -gt 0; do
+  case "$1" in
+  -*=*) optarg=`echo "$1" | sed 's/[-_a-zA-Z0-9]*=//'` ;;
+  *) optarg= ;;
+  esac
+
+  case $1 in
+    --prefix=*)
+      prefix=$optarg
+      ;;
+    --prefix)
+      echo_prefix=yes
+      ;;
+    --exec-prefix=*)
+      exec_prefix=$optarg
+      ;;
+    --exec-prefix)
+      echo_exec_prefix=yes
+      ;;
+    --includedir=*)
+      includedir=$optarg
+      ;;
+    --includedir)
+      echo_includedir=yes
+      ;;
+    --libdir=*)
+      libdir=$optarg
+      ;;
+    --libdir)
+      echo_libdir=yes
+      ;;
+    --version)
+      echo ${major_version}.${minor_version}.${patch_version}
+      ;;
+    --cflags)
+      echo_cflags=yes
+      ;;
+    --libs)
+      echo_libs=yes
+      ;;
+    ssl)
+      lib_ssl=yes
+      ;;
+    smime)
+      lib_smime=yes
+      ;;
+    nss)
+      lib_nss=yes
+      ;;
+    nssutil)
+      lib_nssutil=yes
+      ;;
+    *)
+      usage 1 1>&2
+      ;;
+  esac
+  shift
+done
+
+# Set variables that may be dependent upon other variables
+if test -z "$exec_prefix"; then
+    exec_prefix=`pkg-config --variable=exec_prefix nss`
+fi
+if test -z "$includedir"; then
+    includedir=`pkg-config --variable=includedir nss`
+fi
+if test -z "$libdir"; then
+    libdir=`pkg-config --variable=libdir nss`
+fi
+
+if test "$echo_prefix" = "yes"; then
+    echo $prefix
+fi
+
+if test "$echo_exec_prefix" = "yes"; then
+    echo $exec_prefix
+fi
+
+if test "$echo_includedir" = "yes"; then
+    echo $includedir
+fi
+
+if test "$echo_libdir" = "yes"; then
+    echo $libdir
+fi
+
+if test "$echo_cflags" = "yes"; then
+    echo -I$includedir
+fi
+
+if test "$echo_libs" = "yes"; then
+      libdirs=""
+      if test -n "$lib_ssl"; then
+	libdirs="$libdirs -lssl${major_version}"
+      fi
+      if test -n "$lib_smime"; then
+	libdirs="$libdirs -lsmime${major_version}"
+      fi
+      if test -n "$lib_nss"; then
+	libdirs="$libdirs -lnss${major_version}"
+      fi
+      if test -n "$lib_nssutil"; then
+       libdirs="$libdirs -lnssutil${major_version}"
+      fi
+      echo $libdirs
+fi
+
--- nss-3.17.1/nss/config/nss.pc.in
+++ nss-3.17.1/nss/config/nss.pc.in
@@ -0,0 +1,12 @@
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@
+
+Name: NSS
+Description: Network Security Services
+Version: @NSS_MAJOR_VERSION@.@NSS_MINOR_VERSION@.@NSS_PATCH_VERSION@
+Requires: nspr >= 4.8
+Libs: -L${libdir} -lssl3 -lsmime3 -lnss3 -lnssutil3
+Cflags: -I${includedir}
+
--- nss-3.17.1/nss/manifest.mn
+++ nss-3.17.1/nss/manifest.mn
@@ -10,7 +10,7 @@
 
 RELEASE = nss
 
-DIRS = coreconf lib cmd
+DIRS = coreconf lib cmd config
 
 ifdef NSS_BUILD_GTESTS
 DIRS += external_tests