Flatten uniform arrays

This checkin adds a --flatten-uniform-arrays option which can break
uniform arrays of samplers, textures, or UBOs up into individual
scalars named (e.g) myarray[0], myarray[1], etc.  These appear as
individual linkage objects.

Code notes:

- shouldFlatten internally calls shouldFlattenIO, and shouldFlattenUniform,
  but is the only flattening query directly called.

- flattenVariable will handle structs or arrays (but not yet arrayed structs;
  this is tested an an error is generated).

- There's some error checking around unhandled situations.  E.g, flattening
  uniform arrays with initializer lists is not implemented.

- This piggybacks on as much of the existing mechanism for struct flattening
  as it can.  E.g, it uses the same flattenMap, and the same
  flattenAccess() method.

- handleAssign() has been generalized to cope with either structs or arrays.

- Extended test infrastructure to test flattening ability.

hlsl/hlslParseHelper.h

@@ -83,9 +83,6 @@ public:
     TIntermTyped* handleBinaryMath(const TSourceLoc&, const char* str, TOperator op, TIntermTyped* left, TIntermTyped* right);
     TIntermTyped* handleUnaryMath(const TSourceLoc&, const char* str, TOperator op, TIntermTyped* childNode);
     TIntermTyped* handleDotDereference(const TSourceLoc&, TIntermTyped* base, const TString& field);
-    bool shouldFlatten(const TType&) const;
-    void flatten(const TVariable& variable);
-    TIntermTyped* flattenAccess(TIntermTyped* base, int member);
     void assignLocations(TVariable& variable);
     TFunction& handleFunctionDeclarator(const TSourceLoc&, TFunction& function, bool prototype);
     TIntermAggregate* handleFunctionDefinition(const TSourceLoc&, TFunction&);
@@ -181,6 +178,15 @@ protected:
                        const char* szExtraInfoFormat, TPrefixType prefix,
                        va_list args);
 
+    // Array and struct flattening
+    bool shouldFlatten(const TType& type) const { return shouldFlattenIO(type) || shouldFlattenUniform(type); }
+    TIntermTyped* flattenAccess(TIntermTyped* base, int member);
+    bool shouldFlattenIO(const TType&) const;
+    bool shouldFlattenUniform(const TType&) const;
+    void flatten(const TSourceLoc& loc, const TVariable& variable);
+    void flattenStruct(const TVariable& variable);
+    void flattenArray(const TSourceLoc& loc, const TVariable& variable);
+
     // Current state of parsing
     struct TPragma contextPragma;
     int loopNestingLevel;        // 0 if outside all loops