wmaker: Marked args as unused for compiler in WINGs callback code

The WINGs toolkit dispatch events on widgets using callbacks, which means
having a fixed argument list for the handling function.

It is then correct to not use all the arguments, so this patch adds the
appropriate stuff to avoid a false report from compiler.

Signed-off-by: Christophe CURIS <christophe.curis@free.fr>

src/dockedapp.c

@@ -122,6 +122,9 @@ static void chooseIconCallback(WMWidget * self, void *clientData)
 	AppSettingsPanel *panel = (AppSettingsPanel *) clientData;
 	int result;
 
+	/* Parameter not used, but tell the compiler that it is ok */
+	(void) self;
+
 	panel->choosingIcon = 1;
 
 	WMSetButtonEnabled(panel->browseBtn, False);