Assume termios is available, remove support for termio and sgtty

Assume termios is available, remove support for termio and sgtty

This commit garbage collects the termio and sgtty support.

GDB's terminal handling code still has support for the old termio and
sgtty interfaces in addition to termios.  However, I think it's pretty
safe to assume that for a long, long time, Unix-like systems provide
termios.  GNU/Linux, Solaris, Cygwin, AIX, DJGPP, macOS and the BSDs
all have had termios.h for many years.  Looking around the web, I
found discussions about FreeBSD folks trying to get rid of old sgtty.h
a decade ago:

  https://lists.freebsd.org/pipermail/freebsd-hackers/2007-March/019983.html

So I think support for termio and sgtty in GDB is just dead code that
is never compiled anywhere and is just getting in the way.  For
example, serial_noflush_set_tty_state and the raw<->cooked concerns
mentioned in inflow.c only exist because of sgtty (see
hardwire_noflush_set_tty_state).

Regtested on GNU/Linux.

Confirmed that I can still build Solaris, DJGPP and AIX GDB and that
the resulting GDBs still include the termios.h-guarded code.
Confirmed mingw-w64 GDB still builds and skips the termios.h-guarded
code.

gdb/ChangeLog:
2017-11-06  Pedro Alves  <palves@redhat.com>

	* Makefile.in (SER_HARDWIRE): Update comment.
	(HFILES_NO_SRCDIR): Remove gdb_termios.h.
	* common/gdb_termios.h: Delete file.
	* common/job-control.c: Include termios.h and unistd.h instead of
	gdb_termios.h.
	(gdb_setpgid): Remove HAVE_TERMIOS || TIOCGPGRP preprocessor
	check.
	(have_job_control): Check HAVE_TERMIOS_H instead of HAVE_TERMIOS.
	Remove sgtty code.
	* configure.ac: No longer check for termio.h and sgtty.h.
	* configure: Regenerate.
	* inflow.c: Include termios.h instead of gdb_termios.h.  Replace
	PROCESS_GROUP_TYPE checks with HAVE_TERMIOS_H checks throughout.
	Replace PROCESS_GROUP_TYPE references with pid_t references
	throughout.
	(gdb_getpgrp): Delete.
	(set_initial_gdb_ttystate): Use tcgetpgrp instead of gdb_getpgrp.
	(child_terminal_inferior): Remove comment.  Remove sgtty code.
	(child_terminal_ours_1): Use tcgetpgrp directly instead of
	gdb_getpgrp.  Use serial_set_tty_state instead aof
	serial_noflush_set_tty_state.  Remove sgtty code.
	* inflow.h: Include unistd.h instead of gdb_termios.h.  Replace
	PROCESS_GROUP_TYPE check with HAVE_TERMIOS_H check.
	(inferior_process_group): Now returns pid_t.
	* ser-base.c (ser_base_noflush_set_tty_state): Delete.
	* ser-base.h (ser_base_noflush_set_tty_state): Delete.
	* ser-event.c (serial_event_ops): Update.
	* ser-go32.c (dos_noflush_set_tty_state): Delete.
	(dos_ops): Update.
	* ser-mingw.c (hardwire_ops, tty_ops, pipe_ops, tcp_ops): Update.
	* ser-pipe.c (pipe_ops): Update.
	* ser-tcp.c (tcp_ops): Update.
	* ser-unix.c: Include termios.h instead of gdb_termios.h.  Remove
	HAVE_TERMIOS checks.
	[HAVE_TERMIO] (struct hardwire_ttystate): Delete.
	[HAVE_SGTTY] (struct hardwire_ttystate): Delete.
	(get_tty_state, set_tty_state): Drop termio and sgtty code, and
	assume termios.
	(hardwire_noflush_set_tty_state): Delete.
	(hardwire_print_tty_state, hardwire_drain_output)
	(hardwire_flush_output, hardwire_flush_input)
	(hardwire_send_break, hardwire_raw, hardwire_setbaudrate)
	(hardwire_setstopbits, hardwire_setparity): Drop termio and sgtty
	code, and assume termios.
	(hardwire_ops): Update.
	(_initialize_ser_hardwire): Remove HAVE_TERMIOS check.
	* serial.c (serial_noflush_set_tty_state): Delete.
	* serial.h (serial_noflush_set_tty_state): Delete.
	(serial_ops::noflush_set_tty_state): Delete.

gdb/gdbserver/ChangeLog:
2017-11-06  Pedro Alves  <palves@redhat.com>

	* configure.ac: No longer check for termio.h and sgtty.h.
	* configure: Regenerate.
	* remote-utils.c: Include termios.h instead of gdb_termios.h.
	(remote_open): Check HAVE_TERMIOS_H instead of HAVE_TERMIOS.
	Remove termio and sgtty code.