fdo#68956: Be safe and warn if there are other users of GetText()

Because GetText() now returns a value.

Change-Id: Iafee193771a56b2b3c25f8655fa35a66f31eebe8

starmath/source/mathmlimport.hxx

@@ -256,7 +256,7 @@ public:
     }
 
     sal_Bool GetSuccess()              { return bSuccess; }
-    OUString GetText()                 { return aText; }
+    SAL_WARN_UNUSED_RESULT OUString GetText() { return aText; }
     void SetText(const OUString &rStr) { aText = rStr; }
 
     virtual void SetViewSettings(const com::sun::star::uno::Sequence<com::sun::star::beans::PropertyValue>& aViewProps);