gl::output allocates a pretty large stack buffer, so it has to call _chkstk. This is rather slow, so avoid calling gl::output if perf and tracing are disabled.

BUG=

Review URL: https://codereview.appspot.com/6843043

git-svn-id: https://angleproject.googlecode.com/svn/trunk@1390 736b8ea6-26fd-11df-bfd4-992fa37f6226