Switch from std::mutex and std::unique_lock to marl::mutex and marl::lock.
The marl versions are TSA-friendly replacements, and do not involve the
marl scheduler.

Bug: b/153194656
Change-Id: Ief3758fb0d52b8fcdaa4208d2c25ad04c2d40108
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/43436Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>