ninja: use cc and c++ instead of gcc and g++ by default on non-Windows.

See https://groups.google.com/forum/#!topic/gyp-developer/50IkuJBVGbU .

For Mac specifically:

g++ on my system is not Xcode's g++, but proper FSF GNU GCC g++. This
doesn't hurt Chromium, which sets clang as the compiler by default, but
does hurt projects that don't explicitly specify a compiler, including
the tests.

FSF GNU GCC g++ doesn't understand these options that xcode_emulation.py
adds:

g++: error: unrecognized command line option ‘-fasm-blocks’
g++: error: unrecognized command line option ‘-mpascal-strings’

R=thakis@chromium.org

Review URL: https://codereview.chromium.org/61293005

git-svn-id: http://gyp.googlecode.com/svn/trunk@1791 78cadc50-ecff-11dd-a971-7dbc132099af
3 files changed