Waiting on a fence is problematic if using threaded worker to submit
work since code needs to know if the work has been submitted or not
before doing the wait.
Eliminate the wait by using a serial if available or if no serial check
the file descriptor directly. If no serial it's because we are waiting
on an imported file descriptor. Could call fence.wait in that
case but can also wait on the file descriptor.

Test: angle_end2end_tests --gtest_filter=EGLSyncTest.*/ES2_Vulkan

Bug: b/170312581
Change-Id: I392a5e73ac8f851d0d5bc53f06063568c0c90d2c
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2579042Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Tim Van Patten <timvp@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Courtney Goeltzenleuchter <courtneygo@google.com>