Update Android port

Update Android port

* doc/lispref/os.texi (Desktop Notifications): Revise
documentation for android-notifications-notify to reflect
changes.

* java/org/gnu/emacs/EmacsDesktopNotification.java (display1):
Convert notification importance to a legacy priority between
Android 7.1 and 4.1.

* java/org/gnu/emacs/EmacsPixmap.java (EmacsPixmap): Remove
immutable bitmap constructor, as the underlying Android API
functions are erroneously implemented.

* src/android.c (android_init_emacs_pixmap): Cease searching for
deleted constructor.
(android_create_pixmap_from_bitmap_data): Create a pixmap, then
fill it with the contents of the bitmap, in lieu of employing
the aforementioned constructor.

* src/androidselect.c (Fandroid_notifications_notify): Revise
doc string.