Fix bug of accidentally overriding initial layout location with 0, which does not mean no location. Added in/out structure tests.

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@22120 e7fa87d3-cd2b-0410-9028-fcbf551c1848

glslang/Include/Types.h

@@ -687,6 +687,7 @@ public:
     const char* getStorageQualifierString() const { return ::getStorageQualifierString(qualifier.storage); }
     const char* getPrecisionQualifierString() const { return ::getPrecisionQualifierString(qualifier.precision); }
     TTypeList* getStruct() { return structure; }
+    TTypeList* getStruct() const { return structure; }
 
     int getObjectSize() const
     {
@@ -705,7 +706,6 @@ public:
         return totalSize;
     }
 
-    TTypeList* getStruct() const { return structure; }
     TString& getMangledName()
     {
         if (!mangled) {