Update Android port

Update Android port

* java/org/gnu/emacs/EmacsService.java (sync): Delete function.
* java/org/gnu/emacs/EmacsView.java (handleDirtyBitmap): Erase
with window background.
(onDetachedFromWindow): Only recycle bitmap if non-NULL.
* java/org/gnu/emacs/EmacsWindow.java (background): New field.
(changeWindowBackground): Set it.
* src/android.c (struct android_emacs_service): Remove `sync'.
(android_init_emacs_service): Likewise.
(android_sync): Delete function.
* src/androidfns.c (android_create_tip_frame): Set frame
background color correctly.
(Fx_show_tip): Make the tip frame visible.
* src/androidgui.h: Update prototypes.
* src/androidterm.c (handle_one_android_event): Handle tooltip
movement correctly.