When dcheck_always_on=false, the SPIR-V transformer will strip all debug
information to reduce the SPIR-V binary size.

Running T-Rex shows about 27% reduction in the SPIR-V binary size.

Bug: angleproject:4680
Test: CQ
Change-Id: Id9d0189cdc9c12fa5a1741cf62ef549a533cdf93
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2267358
Commit-Queue: Tim Van Patten <timvp@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>