HLSL: fix for byte address buffers in fn parmeters

Byte address buffers were failing to detect that they were byte address
buffers when used as fn parameters.

Note: this detection is a little awkward, and could be simplified if
it was easy to obtain the declared builtin type for an object.

gtests/Hlsl.FromFile.cpp

@@ -251,6 +251,7 @@ INSTANTIATE_TEST_CASE_P(
         {"hlsl.structbuffer.coherent.frag", "main"},
         {"hlsl.structbuffer.incdec.frag", "main"},
         {"hlsl.structbuffer.fn.frag", "main"},
+        {"hlsl.structbuffer.fn2.comp", "main"},
         {"hlsl.structbuffer.rw.frag", "main"},
         {"hlsl.structbuffer.rwbyte.frag", "main"},
         {"hlsl.structin.vert", "main"},