workaround black screen in viewer on Mac 10.14

Rolling up through https://skia.googlesource.com/third_party/sdl/+/4741821e57853c246024b15790c42deffbaa052a would also fix this, but I'm not quite that dedicated to fixing the SDL build issues involved...

Change-Id: I54e487eef8e3ab3bf9939ce219ef2a1642ca274d
Reviewed-on: https://skia-review.googlesource.com/c/172948
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
1 file changed