immodule: Don't load unsupported IM module

The code would technically allow loading the xim module when X11 support
was not compiled in.

This is probably an artificial concern, because it's pretty hard to
compile XIM support without X11 support, but it makes the code clearer,
so there we go.

gtk/gtkimmodule.c

@@ -118,33 +118,43 @@ static gboolean
 match_backend (GdkDisplay *display,
                const char *context_id)
 {
-#ifdef GDK_WINDOWING_WAYLAND
   if (g_strcmp0 (context_id, "wayland") == 0)
     {
+#ifdef GDK_WINDOWING_WAYLAND
       return GDK_IS_WAYLAND_DISPLAY (display) &&
              gdk_wayland_display_query_registry (display,
                                                  "zwp_text_input_manager_v3");
+#else
+      return FALSE;
+#endif
     }
-#endif
 
-#ifdef GDK_WINDOWING_BROADWAY
   if (g_strcmp0 (context_id, "broadway") == 0)
+#ifdef GDK_WINDOWING_BROADWAY
     return GDK_IS_BROADWAY_DISPLAY (display);
+#else
+    return FALSE;
 #endif
 
-#ifdef GDK_WINDOWING_X11
   if (g_strcmp0 (context_id, "xim") == 0)
+#ifdef GDK_WINDOWING_X11
     return GDK_IS_X11_DISPLAY (display);
+#else
+    return FALSE;
 #endif
 
-#ifdef GDK_WINDOWING_WIN32
   if (g_strcmp0 (context_id, "ime") == 0)
+#ifdef GDK_WINDOWING_WIN32
     return GDK_IS_WIN32_DISPLAY (display);
+#else
+    return FALSE;
 #endif
 
-#ifdef GDK_WINDOWING_QUARTZ
   if (g_strcmp0 (context_id, "quartz") == 0)
+#ifdef GDK_WINDOWING_QUARTZ
     return GDK_IS_QUARTZ_DISPLAY (display);
+#else
+    return FALSE;
 #endif
 
   return TRUE;