Update Android port

Update Android port

* java/org/gnu/emacs/EmacsInputConnection.java
(EmacsInputConnection, performContextMenuAction): New function.
* java/org/gnu/emacs/EmacsNative.java (EmacsNative)
(performContextMenuAction): New function.
* src/android.c (android_get_gc_values): Implement more
efficiently.
* src/androidterm.c (android_handle_ime_event): Pass through
`update' argument to `finish_composing_text'.  Fix thinko.
* src/textconv.c (really_finish_composing_text)
(really_set_composing_text, really_set_composing_region)
(handle_pending_conversion_events_1, finish_composing_text): New
argument `update'.  Notify IME of conversion region changes if
set.
* src/textconv.h: Update structs and prototypes.