The translator emulates atomic counters with a storage buffer array
during translation to Vulkan GLSL.  Glslang wrapper then should assign
set/binding to this buffer.  However, if the atomic counters are
actually unused in the shader, this assignment is never done.

This change adds a small tree transformation for Vulkan that removes any
uniform or interface block declaration that's not active.  In
particular, this makes atomic counter emulation a no-op if no atomic
counters are used.  It also has the benefit of not requiring glslang
wrapper to remove such inactive resources.

Bug: angleproject:4190
Change-Id: I286c199854ec2379558ad1ec48b4d2c4bf5544d0
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1951523
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>