Fix regression in 84a1bc5

Reported by Jochen Sprickerhof, thanks!

Applied patch with minor change (only initialize `i` for XINERAMA).

dmenu.c

@@ -541,7 +541,7 @@ run(void)
 static void
 setup(void)
 {
-	int x, y, i, j = 0;
+	int x, y, i, j;
 	unsigned int du;
 	XSetWindowAttributes swa;
 	XIM xim;
@@ -565,6 +565,7 @@ setup(void)
 	lines = MAX(lines, 0);
 	mh = (lines + 1) * bh;
 #ifdef XINERAMA
+	i = 0;
 	if (parentwin == root && (info = XineramaQueryScreens(dpy, &n))) {
 		XGetInputFocus(dpy, &w, &di);
 		if (mon >= 0 && mon < n)