Fix data race in BlobCache * Re-enable shader cache feature * Improve BlobCache thread-safety test * Improve EGLProgramCacheControlTest to not check the size of the BlobCache, since the shader cache interferes with this. * Include the arguments to ConstructCompiler() and Compile() in the key hash for the shader cache. Bug: angleproject:7036 Change-Id: Ied4e11f9160552f2f9358d99b5656315239ba856 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3851161 Reviewed-by: Cody Northrop <cnorthrop@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Eddie Hatfield <eddiehatfield@google.com>