wmaker: Marked args as unused for compiler in X Error handlers

When an error occurs in X, the Xlib is using a callback mechanism to
execute application code to handle the problem, which means having a
fixed argument list for that application 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/texture.c

@@ -110,6 +110,10 @@ WTexSolid *wTextureMakeSolid(WScreen * scr, XColor * color)
 
 static int dummyErrorHandler(Display * foo, XErrorEvent * bar)
 {
+	/* Parameter not used, but tell the compiler that it is ok */
+	(void) foo;
+	(void) bar;
+
 	return 0;
 }