Fix st with input method.

XFilterEvent need to be called against every event, otherwise it would
missing some message in the xim protocol and misbehave on some im server.

Signed-off-by: Roberto E. Vargas Caballero <k0ga@shike2.com>

st.c

@@ -3786,6 +3786,8 @@ run(void) {
 	/* Waiting for window mapping */
 	while(1) {
 		XNextEvent(xw.dpy, &ev);
+		if(XFilterEvent(&ev, None))
+			continue;
 		if(ev.type == ConfigureNotify) {
 			w = ev.xconfigure.width;
 			h = ev.xconfigure.height;