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

This reverts commit 4e7cdd5a0052aa76bed6f80ec325be19e09e6ab1.

Bug: skia:7058
Change-Id: I3b92c35835cf7a8c04e9218194bf293b790413e0
Reviewed-on: https://skia-review.googlesource.com/57222
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/tests/TransferPixelsTest.cpp b/tests/TransferPixelsTest.cpp
index 722707a..b59495f 100755
--- a/tests/TransferPixelsTest.cpp
+++ b/tests/TransferPixelsTest.cpp
@@ -64,6 +64,10 @@
 
 void basic_transfer_test(skiatest::Reporter* reporter, GrContext* context, GrPixelConfig config,
                          GrSurfaceOrigin origin, bool renderTarget) {
+    if (GrCaps::kNone_MapFlags == context->caps()->mapBufferFlags()) {
+        return;
+    }
+
     // set up the data
     const int kTextureWidth = 16;
     const int kTextureHeight = 16;