Implement toolkit menus on Android

* java/org/gnu/emacs/EmacsActivity.java (onContextMenuClosed):
New function.
* java/org/gnu/emacs/EmacsContextMenu.java (EmacsContextMenu):
New field `itemAlreadySelected'.
(onMenuItemClick): New function.
(inflateMenuItems): Attach onClickListener as appropriate.
(display1): Clear itemAlreadySelected.
(display): Fix runnable synchronization.
* java/org/gnu/emacs/EmacsNative.java (sendContextMenu): New
function.
* java/org/gnu/emacs/EmacsView.java (popupMenu):
(cancelPopupMenu): Set popupactive correctly.

* src/android.c (android_run_select_thread): Fix android_select
again.
(android_wait_event): New function.
* src/android.h: Update prototypes.
* src/androidgui.h (enum android_event_type): New
`ANDROID_CONTEXT_MENU' event.
(struct android_menu_event, union android_event): Add new event.

* src/androidmenu.c (struct android_emacs_context_menu): New
structure.
(android_init_emacs_context_menu): Add `dismiss' method.
(struct android_dismiss_menu_data): New structure.
(android_dismiss_menu, android_process_events_for_menu): New
functions.
(android_menu_show): Set an actual item ID.
(popup_activated): Define when stubify as well.
(Fmenu_or_popup_active_p): New function.
(syms_of_androidmenu): New function.

* src/androidterm.c (handle_one_android_event): Handle context
menu events.
* src/androidterm.h (struct android_display_info): New field for
menu item ID.
* src/emacs.c (android_emacs_init): Call syms_of_androidmenu.
* src/xdisp.c (note_mouse_highlight): Return if popup_activated
on Android as well.

java/org/gnu/emacs/EmacsView.java

@@ -453,6 +453,7 @@ public class EmacsView extends ViewGroup
       return false;
 
     contextMenu = menu;
+    popupActive = true;
 
     /* On API 21 or later, use showContextMenu (float, float).  */
     if (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP)
@@ -469,5 +470,6 @@ public class EmacsView extends ViewGroup
 				       + " popupActive set");
 
     contextMenu = null;
+    popupActive = false;
   }
 };