Revert "Disable GL buffer mapping on TSAN/Mac."

This reverts commit c203e65265ccf0dcf426eafa4fae97b2b99cba7d.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> 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>

TBR=mtklein@google.com,bsalomon@google.com,robertphillips@google.com

Change-Id: Icf0cf40ba4d6e7081971eee2eea0a41033790df7
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:7058
Reviewed-on: https://skia-review.googlesource.com/57220
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
5 files changed