Enabling deqp tests previously skipped due to lack of atomic counters. Fixing
bug found in translator found by new tests.

* Switching atomicCounterDecrement from pre to post decrement
* Added 4 byte alignment check to atomic_uint offset
* Added workaround for NVIDIA D3D bug
* Added globallycoherent to atomic counters

Bug: angleproject:1729
Change-Id: If62ea003826fbe2df0834b905ff3ad7b76328399
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1480867
Commit-Queue: Enrico Galli <enrico.galli@intel.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>