Fix menu and popup race conditions on Android

Fix menu and popup race conditions on Android

* java/org/gnu/emacs/EmacsActivity.java (onContextMenuClosed):
* java/org/gnu/emacs/EmacsContextMenu.java (EmacsContextMenu)
(onMenuItemClick, run):
* java/org/gnu/emacs/EmacsDialog.java (EmacsDialog, onClick)
(createDialog, onDismiss): Take menu event serial, and pass it
along in context menu events.
* java/org/gnu/emacs/EmacsNative.java (sendContextMenu): New
argument.
* src/android.c (sendContextMenu): Pass serial number in event.

* src/androidgui.h (struct android_menu_event): New field
`menu_event_serial'.
* src/androidmenu.c (FIND_METHOD_STATIC)
(android_init_emacs_context_menu): Adjust method declarations.
(android_menu_show, android_dialog_show):
* src/androidterm.c (handle_one_android_event): Expect serial in
context menu events.
* src/androidterm.h: Update prototypes.