Fixes an incompatibility with Libtool 2+.

Rebased on FreeSOLID-2.1.2.

Originally retrieved from Fedora (see:
https://src.fedoraproject.org/rpms/FreeSOLID/raw/rawhide/f/FreeSOLID-2.1.1-configure.patch).

Upstream-status: https://sourceforge.net/p/freesolid/patches/10/

--- FreeSOLID-2.1.1/configure.in.orig	2012-05-24 20:58:30.000000000 +0200
+++ FreeSOLID-2.1.1/configure.in	2012-05-24 21:08:00.932445488 +0200
@@ -1,8 +1,11 @@
 dnl Process this file with autoconf to produce a configure script.
-AC_INIT(sample/sample.cpp)
+AC_INIT
 AC_CONFIG_MACRO_DIR([m4])
+AC_CONFIG_SRCDIR([sample/sample.cpp])
 
-AC_CANONICAL_SYSTEM
+AC_CONFIG_MACRO_DIR([m4])
+
+AC_CANONICAL_TARGET
 PACKAGE=FreeSOLID
 VERSION=2.1.1
 FREESOLID_CURRENT=2
@@ -15,15 +18,14 @@
 
 AM_INIT_AUTOMAKE($PACKAGE, $VERSION)
 
-AM_CONFIG_HEADER(include/config.h)
+AC_CONFIG_HEADERS([include/config.h])
 
 dnl Checks for programs.
-AC_LIBTOOL_WIN32_DLL
 AC_PROG_CXX
 AC_PROG_CC
 AC_PROG_CPP
 AC_PROG_INSTALL
-AC_PROG_LIBTOOL
+LT_INIT([win32-dll])
 
 CPPFLAGS="$CPPFLAGS -I../include -I./include -I. -I../libbroad -I../libmoto"
 AC_SUBST(CPPFLAGS)
@@ -52,11 +54,6 @@
 AC_CHECK_FUNCS(sqrt)
 AC_CHECK_FUNCS(fabs)
 
-AC_OUTPUT([ doc/Makefile 
-            sample/Makefile 
-            Makefile 
-            libbroad/Makefile 
-            libmoto/Makefile 
-            libsolid/Makefile 
-            freesolid-config
-            FreeSOLID.pc])
+AC_CONFIG_FILES([doc/Makefile sample/Makefile Makefile libbroad/Makefile libmoto/Makefile libsolid/Makefile freesolid-config])
+AC_CONFIG_FILES([FreeSOLID.pc])
+AC_OUTPUT