D3D: throw a perf warning for uniform block We had translated an uniform block only containing a large array member into StructuredBuffer instead of cbuffer on D3D backend for slow fxc compile performance issue with dynamic uniform indexing. This patch throw a warning if a uniform block containing a large array member fails to hit the optimization. Bug: angleproject:3682 Change-Id: I33459b559923f16a8dfb70c6f46ec52f68d96e06 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2552365 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jiajia Qin <jiajia.qin@intel.com>