Fix build with gcc 4.5

Based on patch by Dominique Leuenberger
<dominique-gnomezilla@leuenberger.net>

https://bugzilla.gnome.org/show_bug.cgi?id=606719

src/core/core.c

@@ -526,6 +526,9 @@ meta_core_get_menu_accelerator (MetaMenuOp           menu_op,
   
   switch (menu_op)
     {
+    case META_MENU_OP_NONE:
+      name = "none";
+      break;
     case META_MENU_OP_DELETE:
       name = "close";
       break;

src/core/window.c

@@ -7067,9 +7067,12 @@ menu_callback (MetaWindowMenu *menu,
     {
       meta_verbose ("Menu op %u on %s\n", op, window->desc);
 
-      /* op can be 0 for none */
       switch (op)
         {
+        case META_MENU_OP_NONE:
+          /* nothing */
+          break;
+
         case META_MENU_OP_DELETE:
           meta_window_delete (window, timestamp);
           break;
@@ -7157,10 +7160,6 @@ menu_callback (MetaWindowMenu *menu,
           meta_window_shove_titlebar_onscreen (window);
           break;
 
-        case 0:
-          /* nothing */
-          break;
-
         default:
           meta_warning (G_STRLOC": Unknown window op\n");
           break;
@@ -7213,8 +7212,8 @@ meta_window_show_menu (MetaWindow *window,
       window->display->window_with_menu = NULL;
     }
 
-  ops = 0;
-  insensitive = 0;
+  ops = META_MENU_OP_NONE;
+  insensitive = META_MENU_OP_NONE;
 
   ops |= (META_MENU_OP_DELETE | META_MENU_OP_MINIMIZE | META_MENU_OP_MOVE | META_MENU_OP_RESIZE);
 

src/include/common.h

@@ -52,6 +52,7 @@ typedef enum
 
 typedef enum
 {
+  META_MENU_OP_NONE        = 0,
   META_MENU_OP_DELETE      = 1 << 0,
   META_MENU_OP_MINIMIZE    = 1 << 1,
   META_MENU_OP_UNMAXIMIZE  = 1 << 2,