fix a warning

ghc/rts/win32/ConsoleHandler.c

@@ -182,7 +182,7 @@ void markSignalHandlers (evac_fn evac)
 {
     if (console_handler >= 0) {
 	StgPtr p = deRefStablePtr((StgStablePtr)console_handler);
-	evac((StgClosure**)&p);
+	evac((StgClosure**)(void *)&p);
     }
 }