WIP: HLSL: add structuredbuffer pass by reference in fn params

This PR adds the ability to pass structuredbuffer types by reference
as function parameters.

It also changes the representation of structuredbuffers from anonymous
blocks with named members, to named blocks with pseudonymous members.
That should not be an externally visible change.

glslang/MachineIndependent/SymbolTable.cpp

@@ -103,7 +103,11 @@ void TType::buildMangledName(TString& mangledName)
             mangledName += "M";
         break;
     case EbtStruct:
-        mangledName += "struct-";
+    case EbtBlock:
+        if (basicType == EbtStruct)
+            mangledName += "struct-";
+        else
+            mangledName += "block-";
         if (typeName)
             mangledName += *typeName;
         for (unsigned int i = 0; i < structure->size(); ++i) {