Add upstream patch to make the build work with non-base (ie. newer) GCCs.

The build was failing with, for example, lang/gcc48:

In file included from /usr/ports/devel/cmake/work/cmake-3.2.3/Source/cmGlobalNinjaGenerator.cxx:14:0:
/usr/ports/devel/cmake/work/cmake-3.2.3/Source/cmGeneratorExpressionEvaluationFile.h:39:64: error: 'mode_t' has not been declared

std::map<std::string, std::string> &outputFiles, mode_t perm);