Add missing NSOpenGLPFAMultisample attribute to the OpenGL pixel format.

According to the documentation at
https://developer.apple.com/documentation/appkit/nsopenglpfamultisample
this attribute is necessary to enable MSAA antialiasing.

(Unfortunately, even with this change, MSAA is still not working
properly in OpenGL.)

Change-Id: I1f59a4659d4891fc239ab4c56df7b134f0f5f2a3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/287996
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
1 file changed