Avoid data race in overflow check. `mSerial + 1 > mSerial` involves reading the value multiple times which results in a data race. Bug: angleproject:6633 Change-Id: Iae289ba2ee54190703f16f60319d10988da46cb9 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3381854 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Roman Lavrov <romanl@google.com>