Adding more warning in core

I figured out the reason for the lack of warnings on Linux that caused the Mac build break. Some warnings were explicitly disabled in "core" on Linux. I re-enabled them.
Review URL: https://codereview.chromium.org/12667012

git-svn-id: http://skia.googlecode.com/svn/trunk/gyp@8080 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed