HLSL: cbuffer and tbuffer grammar and production.

Test/hlsl.buffer.frag

@@ -0,0 +1,22 @@
+cbuffer {
+    float4 v1;
+};
+
+tbuffer {
+    float4 v2;
+};
+
+cbuffer cbufName : register(b2) {
+    float4 v3;
+    int i3 : packoffset(c1.y);
+};
+
+tbuffer tbufName : register(b8) {
+    float4 v4 : packoffset(c1);
+    int i4 : packoffset(c3);
+};
+
+float4 PixelShaderFunction(float4 input) : COLOR0
+{
+    return input + v1 + v2 + v3 + v4;
+}