Disable GL buffer mapping on TSAN/Mac.

Also reverts 65e706379657d64371012c2e95ccf1354d741145 which disabled buffer mapping in GrResourceProvider::createPatternedIndexBuffer.

Bug: skia:7058
Change-Id: I6816abe53251e1cd8e92eae41b8cdbe45218a341
Reviewed-on: https://skia-review.googlesource.com/50100
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
5 files changed