Use a mutex to guard against the object init. The accesses to the
cache internals are internally synchronized. There is a Vulkan ext
that allows for external cache synchronization that we could
investigate at some point.
Detected by looking at MultithreadingTest with TSAN enabled.
Bug: b/168744561
Change-Id: I1d4744e1aa970bcd57cac49f7ecaf8c238ea61c2
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2415183
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
