icc: use compound literal rather than static object to return pointer

thus make mkcmessage reentrant (and a macro, rather than a function)

icc.c

@@ -78,20 +78,6 @@ void setstringprop(Window w, Atom a, char *str)
     XSetTextProperty(dpy, w, &txtp, a);
 }
 
-XEvent *mkcmessage(Window w, Atom a, long x)
-{
-  static XEvent ev;
-
-  memset(&ev, 0, sizeof(ev));
-  ev.xclient.type = ClientMessage;
-  ev.xclient.window = w;
-  ev.xclient.message_type = a;
-  ev.xclient.format = 32;
-  ev.xclient.data.l[0] = x;
-  ev.xclient.data.l[1] = CurrentTime;
-  return &ev;
-}
-
 void getwmstate(Client *c)
 {
   Atom *p;

icc.h

@@ -24,4 +24,13 @@ extern Atom wm_state, wm_change_state, wm_protocols, wm_delete, wm_take_focus, w
 #define Psizeright 8
 #define Psizetrans 16
 
+
+#define mkcmessage(w, a, x, ...) (&(XEvent){.xclient = { \
+  .type = ClientMessage, \
+  .window = (w), \
+  .message_type = (a), \
+  .format = 32, \
+  .data.l = {(long)(x), CurrentTime, __VA_ARGS__}, \
+}})
+
 #endif