Fix the mac build of the SampleApp.

My call to glViewport breaks the mac build, but benefits the Android
and linux builds.  Fix the mac build until I come up with a better
solution.

Reviewed at http://codereview.appspot.com/4628042/


git-svn-id: http://skia.googlecode.com/svn/trunk@1612 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed