Update Android port

Update Android port

* doc/emacs/android.texi (Android Startup, Android Environment):
Document that restrictions on starting Emacs have been lifted.

* java/README: Document Java for Emacs developers and how the
Android port works.

* java/org/gnu/emacs/EmacsApplication.java (EmacsApplication)
(findDumpFile): New function.
(onCreate): Factor out dump file finding functions to there.

* java/org/gnu/emacs/EmacsNative.java (EmacsNative): Update
function declarations.
* java/org/gnu/emacs/EmacsNoninteractive.java
(EmacsNoninteractive): New class.

* java/org/gnu/emacs/EmacsService.java (EmacsService, getApkFile)
(onCreate): Pass classpath to setEmacsParams.
* java/org/gnu/emacs/EmacsThread.java (EmacsThread): Make run an
override.
* lisp/loadup.el: Don't dump on Android when noninteractive.
* lisp/shell.el (shell--command-completion-data): Handle
inaccessible directories.
* src/Makefile.in (android-emacs): Link with gnulib.
* src/android-emacs.c (main): Implement to launch app-process
and then EmacsNoninteractive.
* src/android.c (setEmacsParams): New argument `class_path'.
Don't set stuff up when running noninteractive.
* src/android.h (initEmacs): Likewise.
* src/androidfont.c (init_androidfont):
* src/androidselect.c (init_androidselect): Don't initialize
when running noninteractive.
* src/emacs.c (load_pdump): New argument `dump_file'.
(android_emacs_init): Give new argument `dump_file' to
`load_pdump'.
* src/sfntfont-android.c (init_sfntfont_android): Don't
initialize when running noninteractive.