Update Android port

Update Android port

* java/org/gnu/emacs/EmacsNative.java (EmacsNative): New
function requestSelectionUpdate.
* java/org/gnu/emacs/EmacsView.java (onCreateInputConnection):
Call it instead of losing if getting the current selection
fails.
* src/android-asset.h (AAsset_seek): Define stub.
* src/android.c (android_open): Take mode_t.
(android_open_asset, android_close_asset, android_asset_read_quit)
(android_asset_read, android_asset_lseek, android_asset_fstat):
New functions.
* src/android.h (struct android_fd_or_asset): Update prototypes.
* src/androidgui.h (enum android_ime_operation): Add new
operation to update the selection position.
* src/androidterm.c (android_handle_ime_event): Handle new
operation.
(requestSelectionUpdate): New function.
* src/fileio.c (close_file_unwind_emacs_fd): New function.
(Fcopy_file, union read_non_regular, read_non_regular)
(Finsert_file_contents): Use optimized codepath to insert
Android asset files.
* src/frame.h (enum text_conversion_operation): New operation.
* src/textconv.c (really_request_point_update)
(handle_pending_conversion_events_1, request_point_update): New
functions.
* src/textconv.h: Update prototypes.