It appears that older Qualcomm driver has some serious performance issue
with specialization constant. This does not happen with latest
development driver. This adds a feature flag to pick driver uniform path
for older driver.

Bug: b/173636783
Change-Id: Ia494fedbb1e0e69fbd8c44f8457c1bc30bc9fa4b
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2547809Reviewed-by: Tim Van Patten <timvp@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Ian Elliott <ianelliott@google.com>
Commit-Queue: Charlie Lao <cclao@google.com>