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

--- a/src/mingw-w64.mk	Fri Sep 01 23:20:44 2017 -0700
+++ b/src/mingw-w64.mk	Mon Jul 31 16:53:21 2017 -0400
@@ -3,8 +3,8 @@
 
 PKG             := mingw-w64
 $(PKG)_IGNORE   :=
-$(PKG)_VERSION  := 4.0.6
-$(PKG)_CHECKSUM := cc9ef3be9bb31ee3fdc4731d214034be5483270d
+$(PKG)_VERSION  := 5.0.2
+$(PKG)_CHECKSUM := bb5409f034abb7c021b3e1c14db433fd253cbb59
 $(PKG)_SUBDIR   := $(PKG)-v$($(PKG)_VERSION)
 $(PKG)_FILE     := $(PKG)-v$($(PKG)_VERSION).tar.bz2
 $(PKG)_URL      := http://$(SOURCEFORGE_MIRROR)/project/$(PKG)/$(PKG)/$(PKG)-release/$($(PKG)_FILE)