Fix bug: non-cygwin actions incorrectly run options through _FixPath.
Fix bug: non-cygwin actions incorrectly run options through _FixPath.

This adds an additional heuristic to the existing one. Now if an option begins
with either a '/' OR a '-', it assumes it's not a strict path.

Added a TODO which notes that the existing (and new) behavior will miss options
such as '--opt=a/posix/path', and '/opt:a/posix/path'.
Review URL: https://chromiumcodereview.appspot.com/10829049

csulmone/gyp,csulmone/gyp,csulmone/gyp,csulmone/gyp