Changes VkTimeLineSemaphore::Shared::wait to pass on already
signalled semaphores.

Bug: b/188565298
Change-Id: I52089aca20d79392b1d9fb9ae2e0e04e8c91c6ff
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/54908
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Sean Risser <srisser@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>