HLSL: Partially address issue #463: accept GLSL layout(...).

This includes all "per variable" layout qualifiers, but the
key ones mattering and tested for now are:
  set=
  binding=
  constant_id=
  push_constant

gtests/Hlsl.FromFile.cpp

@@ -112,6 +112,7 @@ INSTANTIATE_TEST_CASE_P(
         {"hlsl.intrinsics.negative.comp", "ComputeShaderFunction"},
         {"hlsl.intrinsics.negative.frag", "PixelShaderFunction"},
         {"hlsl.intrinsics.negative.vert", "VertexShaderFunction"},
+        {"hlsl.layout.frag", "main"},
         {"hlsl.load.2dms.dx10.frag", "main"},
         {"hlsl.load.array.dx10.frag", "main"},
         {"hlsl.load.basic.dx10.frag", "main"},