SkDEBUGF: use __VA_ARGS__

Change-Id: I42a47e821ff7a7f6cec65b38a8216cabbf0acfce
Reviewed-on: https://skia-review.googlesource.com/139860
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
15 files changed