Further simplify Xinerama init and re-init on XRR events.

While testing for Xinerama during setup was done display-wide, each time
XineramaQueryScreens() is called either in start-up or due to an XRR
event, the library re-tests for the Xinerama extension anyway before
moving on; so the initial test is redundant and allows another global to
go away with one other change: always fill in sc->xinerama (and _no),
regardless of the success of malloc in XineramaQueryScreens(), and use
it to see if Xinerama dimensions exist when asked by client and/or menu
code.

calmwm.c

@@ -44,7 +44,7 @@ Cursor				 Cursor_resize;
 struct screen_ctx_q		 Screenq = TAILQ_HEAD_INITIALIZER(Screenq);
 struct client_ctx_q		 Clientq = TAILQ_HEAD_INITIALIZER(Clientq);
 
-int				 HasXinerama, HasRandr, Randr_ev;
+int				 HasRandr, Randr_ev;
 struct conf			 Conf;
 
 static void	sigchld_cb(int);
@@ -97,7 +97,7 @@ main(int argc, char **argv)
 static void
 dpy_init(const char *dpyname)
 {
-	int	i, fake;
+	int	i;
 
 	XSetErrorHandler(x_errorhandler);
 
@@ -110,9 +110,6 @@ dpy_init(const char *dpyname)
 	XSync(X_Dpy, False);
 	XSetErrorHandler(x_errorhandler);
 
-	if (XineramaQueryExtension(X_Dpy, &fake, &fake) == 1 &&
-	    ((HasXinerama = XineramaIsActive(X_Dpy)) == 1))
-		HasXinerama = 1;
 	HasRandr = XRRQueryExtension(X_Dpy, &Randr_ev, &i);
 }
 

screen.c

@@ -74,21 +74,11 @@ screen_updatestackingorder(struct screen_ctx *sc)
 void
 screen_init_xinerama(struct screen_ctx *sc)
 {
-	XineramaScreenInfo	*info;
-	int			 no;
-
-	if (HasXinerama == 0 || XineramaIsActive(X_Dpy) == 0) {
-		HasXinerama = 0;
-		sc->xinerama_no = 0;
-	}
+	XineramaScreenInfo	*info = NULL;
+	int			 no = 0;
 
-	info = XineramaQueryScreens(X_Dpy, &no);
-	if (info == NULL) {
-		/* Is xinerama actually off, instead of a malloc failure? */
-		if (sc->xinerama == NULL)
-			HasXinerama = 0;
-		return;
-	}
+	if (XineramaIsActive(X_Dpy))
+		info = XineramaQueryScreens(X_Dpy, &no);
 
 	if (sc->xinerama != NULL)
 		XFree(sc->xinerama);
@@ -105,7 +95,7 @@ screen_find_xinerama(struct screen_ctx *sc, int x, int y)
 	XineramaScreenInfo	*info;
 	int			 i;
 
-	if (HasXinerama == 0)
+	if (sc->xinerama == NULL)
 		return (NULL);
 
 	for (i = 0; i < sc->xinerama_no; i++) {