Non-functional: Fix #1231: remove duplicated code.

glslang/Include/ConstantUnion.h

@@ -595,9 +595,6 @@ public:
         if (! unionArray || ! rhs.unionArray)
             return false;
 
-        if (! unionArray || ! rhs.unionArray)
-            return false;
-
         return *unionArray == *rhs.unionArray;
     }
     bool operator!=(const TConstUnionArray& rhs) const { return ! operator==(rhs); }