[PATCH] Make clang tools ignore -fcolor-diagnostics and -fdiagnostics-color retrieved from the compilation database.

[Alexander Kornienko]

  -fcolor-diagnostics is by default set to auto, which means it colors output when it detects a capable terminal. And if we want to force clang tools color output, we need a separate flag for tools, and not rely on what is in the compilation database.

  BTW, the problem was discovered by r182878, where -fcolor-diagnostics was added to cmake+ninja configuration to force clang color output when run by ninja.

http://llvm-reviews.chandlerc.com/D917