* inftarg.c: Remove unused include of terminal.h.

	* inftarg.c: Remove unused include of terminal.h.
	* signals.h: Don't undefine signals anymore.
	* main.c: Use job_control from serial.h.
	* fork-child.c (fork_inferior): Use gdb_setpgid.
	* serial.h, ser-unix.c, ser-go32.c: Provide gdb_setpgid.
	* utils.c (quit): Use current_target->to_terminal_ours to figure
	out whether we care about lack of job control, rather than __GO32__.
	* utils.c: Include serial.h not terminal.h
	(quit): Use job_control not TIOCGPGRP.
	* terminal.h: Don't undefine TIOCGPGRP.
	* serial.h, ser-unix.c, ser-go32.c, ser-tcp.c: Add SERIAL_FLUSH_OUTPUT.
	* utils.c (quit): Use it.
	* serial.h: Add SERIAL_UN_FDOPEN.
	* utils.c (quit): Use it.
	* ser-unix.c: Add process group to ttystate.
	[HAVE_SGTTY]: Add tchars, ltchars, and lmode to ttystate.
	* inflow.c: Include serial.h not terminal.h.
	Use serial.h stuff to replace most of the maze of #ifdef's.
	* inflow.c, main.c, inferior.h: make gdb_has_a_terminal a function.
	* serial.h: Document SERIAL_SET_TTY_STATE as being immediate.
	* ser-unix.c: Use TIOCSETN not TIOCSETP so it is true.
	* serial.h, ser-unix.c, ser-go32.c, ser-tcp.c:
	Add SERIAL_PRINT_TTY_STATE, SERIAL_NOFLUSH_SET_TTY_STATE, and
	SERIAL_SET_PROCESS_GROUP.
	* inflow.c: Use them.
	* config/xm-svr4.h, config/rs6000/xm-rs6000.h, config/sparc/sun4os4.h:
	Define HAVE_TERMIOS.
	* Various: Remove all use of TIOC*_BROKEN.