Update Android port

Update Android port

* src/android.c (android_is_special_directory): New function.
(android_get_asset_name, android_content_name_p)
(android_get_content_name):
* src/android.h (android_is_special_directory)
(JNI_STACK_ALIGNMENT_PROLOGUE):
* src/fileio.c (check_mutable_filename):
* src/filelock.c (WTMP_FILE, make_lock_file_name):
* src/inotify.c (IN_ONLYDIR, Finotify_add_watch): Factor out
checks against asset and content directories to that function.