arch: move X11 locale init into X11 backend display_open

XSupportsLocale and XSetLocaleModifiers in main.c were the last
direct Xlib calls in src/main.c.  Move them into x11_display_open
(guarded by I18N) where they naturally belong.  The Wayland backend
does not need them — locale handling for native Wayland clients is
just standard libc, and XWayland clients still receive locale-aware
input via the wmaker-attached XWayland server's own setup.

main.c is now Xlib-free.

src/backend/x11/x11_backend.c

@@ -107,6 +107,15 @@ struct WBackendScreen {
 static void *
 x11_display_open(const char *name)
 {
+    /* Locale init must happen before XOpenDisplay so the X server-side
+     * input handling honors LC_CTYPE.  Previously called from main.c. */
+#ifdef I18N
+    if (!XSupportsLocale())
+        wwarning(_("X server does not support locale"));
+    if (XSetLocaleModifiers("") == NULL)
+        wwarning(_("cannot set locale modifiers"));
+#endif
+
     Display *d = XOpenDisplay(name);
     if (!d)
         return NULL;

src/main.c

@@ -748,14 +748,6 @@ static int real_main(int argc, char **argv)
 	bind_textdomain_codeset(MENU_TEXTDOMAIN, "UTF-8");
 #endif
 	textdomain("WindowMaker");
-
-	if (!XSupportsLocale()) {
-		wwarning(_("X server does not support locale"));
-	}
-
-	if (XSetLocaleModifiers("") == NULL) {
-		wwarning(_("cannot set locale modifiers"));
-	}
 #endif
 
 	if (w_global.locale) {