Ticket is a synchronization primitive used to serially order execution.

Bug: b/139010488
Change-Id: I7f34556609b0206c87f57be9c6bc14b21096f8f4
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/34818Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>