Respect Language & Input preferences under Android

Respect Language & Input preferences under Android

* doc/emacs/android.texi (Android Environment):

* doc/emacs/cmdargs.texi (General Variables): Mention the manner
in which the default language environment is selected on
Android.

* lisp/startup.el (normal-top-level): If android and
initial-window-system, call android-locale-for-system-language
for the default locale name.

* lisp/term/android-win.el (android-locale-for-system-language):
New function.

* src/androidfns.c (syms_of_androidfns_for_pdumper): New
function.
(syms_of_androidfns) <Vandroid_os_language>: New variable.
Call syms_of_androidfns_for_pdumper both now and after
loading the dump image.

(cherry picked from commit de25aaa11a8ef264c6f76841daa7e2a721c60937)