gcc: update to 7.1 with tools * src/build-gcc.mk: update version 7.1.0 * src/cloog.mk: update 0.18.4 * src/gmp.mk: update 6.1.2 * src/isl.mk: update 0.16.1, add no-undefined flag * src/mpfr.mk: update 3.1.6 * src/native-gcc.mk: update 7.1.0 * src/isl-1-fixes.patch: removed file * dist-files.mk: remove reference to patch files, add mingw-w64 patch * src/build-gcc-1-mingw-float.patch: removed patch * src/native-gcc-1-mingw-float.patch: removed patch * src/build-gcc-2-intrinsics.patch: removed patch * src/native-gcc-2-intrinsics.patch: removed patch * src/mingw-w64.mk: update to 5.0.2 * src/gcc-1-mingw-float.patch: remove patch * src/gcc-2-darwin-no-pie.patch: remove patch * src/mingw-w64-2-pthreads.patch: new file * src/pthreads.mk: apply mingw patches to mingw sources before running configure

diff -ur libffi-3.0.11-orig/configure libffi-3.0.11/configure
--- libffi-3.0.11-orig/configure	2012-04-11 23:13:17 -0400
+++ libffi-3.0.11/configure	2013-07-12 11:13:45 -0400
@@ -14572,7 +14572,7 @@
     toolexecdir='$(libdir)/gcc-lib/$(target_alias)'
     toolexeclibdir='$(libdir)'
   fi
-  multi_os_directory=`$CC -print-multi-os-directory`
+  #multi_os_directory=`$CC -print-multi-os-directory`
   case $multi_os_directory in
     .) ;; # Avoid trailing /.
     *) toolexeclibdir=$toolexeclibdir/$multi_os_directory ;;