HLSL: add in/out/inout qualifiers.

Test/hlsl.inoutquals.frag

@@ -0,0 +1,25 @@
+struct PS_OUTPUT
+{
+    float4 Color : SV_Target0;
+    float  Depth : SV_Depth;
+};
+
+void MyFunc(in float x, out float y, inout float z)
+{
+    y = x;
+    z = y;
+    x = -1; // no effect since x = in param
+}
+
+PS_OUTPUT main(noperspective in float4 inpos : SV_Position)
+{
+   PS_OUTPUT psout;
+
+   float x = 7, y, z = 3;
+   MyFunc(x, y, z);
+
+   psout.Color = float4(x, y, z, 1);
+   psout.Depth = inpos.w;
+
+   return psout;
+}