WebKit compiles with -Wglobal-constructors, so they want this. I decided
to do -Wexit-time-destructors at the same time.

Bug: angleproject:3439
Bug: angleproject:1459
Change-Id: I4b44ae4f8e6f066e07dc7f9f6ced9a5d49dc8f8a
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1738438
Commit-Queue: James Darpinian <jdarpinian@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>