0032460: Coding Rules - eliminate CLang warning -Wunused-but-set-variable

Code has been adjusted to suppress -Wunused-but-set-variable warnings.

DRAWEXE.wasm, compiler flags have been moved to linker flags
to eliminiate -Wunused-command-line-argument warnings.

src/XmlMDF/XmlMDF.cxx

@@ -178,6 +178,8 @@ Standard_Boolean XmlMDF::FromTo (const XmlObjMgt_Element&           theElement,
       // check for error
       if (subcount < 0)
         return Standard_False;
+
+      (void )count; // unused but set for debug
       count += subcount;
     }
     //anElem = (const XmlObjMgt_Element &) anElem.getNextSibling();