Fix some tests and do some cleanup.

test/codegen/constant_buffer.golden

@@ -0,0 +1,18 @@
+cbuffer camera : register(b0)
+{
+    float4x4 projection;
+    float4x4 view;
+}
+
+float4 vs_main(float4 pos : POSITION) : SV_POSITION
+{
+    float4 mv = mul(camera.view, pos);
+    float4 mvp = mul(camera.projection, mv);
+    return mvp;
+}
+
+float4 ps_main() : SV_TARGET
+{
+    return float4(0.5f, 0.5f, 0.5f, 1.0f);
+}
+