Added usage hint for --auto-sampled-textures, added test cases

Test/hlsl.autosampledtextures.frag

@@ -0,0 +1,21 @@
+Texture2D g_tColor;
+
+SamplerState g_sAniso;
+
+struct PS_INPUT
+{
+    float2 vTextureCoords : TEXCOORD2 ;
+} ;
+
+struct PS_OUTPUT
+{
+    float4 vColor : SV_Target0 ;
+} ;
+
+PS_OUTPUT MainPs ( PS_INPUT i )
+{
+    PS_OUTPUT ps_output ;
+
+    ps_output . vColor = g_tColor . Sample ( g_sAniso , i . vTextureCoords . xy ) ;
+    return ps_output ;
+}