Instead of walking through uniform locations, walk through
the uniforms themselves and emit arrayed uniforms, which consume
multiple locations.

Test: MEC capture of Manhattan on Windows
Bug: angleproject:3662
Change-Id: Ifd25528721982847d4f0938f469a914a1cb908c5
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2175994
Commit-Queue: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>