* 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.
