turn on clang.msan and gcc.tsan on Linux

I _think_ this should cleverly silently disable these configs when
running on a Mac.

Change-Id: Idd2e059f75c249207b1bf146b27300f7be772b8f
Reviewed-on: https://skia-review.googlesource.com/94961
Reviewed-by: Brian Osman <brianosman@google.com>
4 files changed