* remote-fileio.c: New file implementing the remote File-I/O protocol.
* remote-fileio.h: New header file defining remote File-I/O interface.
* remote.c (remote_write_bytes, remote_read_bytes): Remove
static storage class.
(remote_wait, remote_async_wait): Call remote_fileio_request() on
'F' packet.
(_initialize_remote): Call initialize_remote_fileio().
* remote.h: Declare remote_write_bytes() and remote_read_bytes().
* Makefile.in (REMOTE_OBS): Add remote-fileio.o
(SFILES): Add remote-fileio.c.
Add dependencies for building remote-fileio.o. Add remote-fileio.h to
dependencies for building remote.o.
* defs.h: Declare gdb_stdin, gdb_stdtargerr and gdb_stdtargin.
* main.c: New ui_file gdb_stdin, gdb_stdtargerr and gdb_stdtargin.
(captured_main): Initialize new ui_files.
* ui-file.c: Add read and fgets input functions.
(ui_file_new): set ui_file_fputs and ui_file_read to null functions.
(null_file_read): New function.
(ui_file_read): New function.
(set_ui_file_read): New function.
(stdio_file_read): New function.
* ui-file.h: New type ui_file_read_ftype.
(set_ui_file_read): Declare.
(ui_file_read): Declare.