replace gm_fprintf() calls with SkDebugf()

BUG=skia:1221
R=bsalomon@google.com

Author: epoger@google.com

Review URL: https://codereview.chromium.org/181933002

git-svn-id: http://skia.googlecode.com/svn/trunk@13613 2bbb7eff-a529-9590-31e7-b0007b416f81
3 files changed