Add GYP build for the src/tools directory on Mac and Linux.

This GYP-ifies the src/processor and src/common directories on those platforms
as well. The Makefile build uses much more granular unittest executables, so
the new processor_unittests does not yet link because of multiple main() symbols,
but this will be fixed later.

Update issue 575

R=mark@chromium.org

Review URL: https://breakpad.appspot.com/10674002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1358 4c0a9323-5329-0410-9bdc-e9ce6186880e