Fix make generator when using target name to build. (If target.c exists in the same directory, Make's implicit rule would try to build target using the actual target + target.c again.)  By marking the target phony, we tell make that we don't actually want to generate that output file in the  current dir.
Fix make generator when using target name to build. (If target.c exists in the same directory, Make's implicit rule would try to build target using the actual target + target.c again.)  By marking the target phony, we tell make that we don't actually want to generate that output file in the  current dir.

BUG=http://code.google.com/p/gyp/issues/detail?id=67

Review URL: http://codereview.chromium.org/185011
Patch from Matt Mueller <mattm@chromium.org>.
old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google