autoconf: Enable cross-compilation

pkgs/development/compilers/gcc/6/fix-objdump-check.patch

@@ -0,0 +1,43 @@
+commit 4c38abe0967bad78dd6baa61c86923e4d4b346d3
+Author: Ben Gamari <ben@smart-cactus.org>
+Date:   Sun Nov 5 13:14:19 2017 -0500
+
+    Fix it
+
+diff --git a/config/gcc-plugin.m4 b/config/gcc-plugin.m4
+index dd06a58..f4435b8 100644
+--- a/config/gcc-plugin.m4
++++ b/config/gcc-plugin.m4
+@@ -13,6 +13,32 @@ dnl the same distribution terms as the rest of that program.
+ # Sets the shell variables enable_plugin and pluginlibs.
+ AC_DEFUN([GCC_ENABLE_PLUGINS],
+   [# Check for plugin support
++
++   # Figure out what objdump we will be using.
++   AS_VAR_SET_IF(gcc_cv_objdump,, [
++   if test -f $gcc_cv_binutils_srcdir/configure.ac \
++        && test -f ../binutils/Makefile \
++        && test x$build = x$host; then
++   	# Single tree build which includes binutils.
++   	gcc_cv_objdump=../binutils/objdump$build_exeext
++   elif test -x objdump$build_exeext; then
++   	gcc_cv_objdump=./objdump$build_exeext
++   elif ( set dummy $OBJDUMP_FOR_TARGET; test -x $[2] ); then
++           gcc_cv_objdump="$OBJDUMP_FOR_TARGET"
++   else
++           AC_PATH_PROG(gcc_cv_objdump, $OBJDUMP_FOR_TARGET)
++   fi])
++   
++   AC_MSG_CHECKING(what objdump to use)
++   if test "$gcc_cv_objdump" = ../binutils/objdump$build_exeext; then
++   	# Single tree build which includes binutils.
++   	AC_MSG_RESULT(newly built objdump)
++   elif test x$gcc_cv_objdump = x; then
++   	AC_MSG_RESULT(not found)
++   else
++   	AC_MSG_RESULT($gcc_cv_objdump)
++   fi
++
+    AC_ARG_ENABLE(plugin,
+    [AS_HELP_STRING([--enable-plugin], [enable plugin support])],
+    enable_plugin=$enableval,

pkgs/development/tools/misc/autoconf/default.nix

@@ -8,7 +8,8 @@ stdenv.mkDerivation rec {
     sha256 = "113nlmidxy9kjr45kg9x3ngar4951mvag1js2a3j8nxcz34wxsv4";
   };
 
-  buildInputs = [ m4 perl ];
+  nativeBuildInputs = [ m4 perl ];
+  buildInputs = [ m4 ];
 
   # Work around a known issue in Cygwin.  See
   # http://thread.gmane.org/gmane.comp.sysutils.autoconf.bugs/6822 for