Update build-gcc, nsis to compile when in w64 mode. * src/build-binutils.mk: add windows 64 conditionals to binutils to compile multilib * src/build-gcc.mk:add windows 64 conditionals to gcc to compile multilib * src/nsis.mk: add PKG_BUILD target for windows 64 * src/win64-nsis.patch: new file. * dist-files.mk: add reference to win64-nsis.patch.

diff -ur a/include/isl/int.h b/include/isl/int.h
--- a/include/isl/int.h	2012-11-29 03:47:32.000000000 -0500
+++ b/include/isl/int.h	2014-02-19 02:44:04.311137242 -0500
@@ -14,7 +14,7 @@
 #include <string.h>
 #include <gmp.h>
 #if defined(__cplusplus)
-#include <iostream>
+#include <ostream>
 #endif
 
 #if defined(__cplusplus)