Assume POSIX 1003.1-1988 or later for signal.h.

Assume POSIX 1003.1-1988 or later for signal.h.

Exceptions: do not assume SIGCONT, SIGSTOP, SIGTSTP, SIGTTIN,
SIGTTOU, SIGUSR1, SIGUSR2, as Microsoft platforms lack these.
* admin/CPP-DEFINES (SIGALRM, SIGCHLD, SIGHUP, SIGKILL, SIGPIPE, SIGQUIT):
Remove.
(SIGTRAP): Remove this one too, as config.h no longer defines it.
* admin/merge-gnulib (GNULIB_MODULES): Add sig2str.
* configure.ac (PTY_OPEN, PTY_TTY_NAME_SPRINTF):
Use SIGCHLD rather than SIGCLD.
* lib/sig2str.c, lib/sig2str.h, m4/sig2str.m4: New files, from gnulib.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* lib/makefile.w32-in (GNULIBOBJS): Add $(BUILD)/sig2str.$(O).
* src/process.c [subprocesses]: Include <c-ctype.h>, <sig2str.h>.
(deleted_pid_list, Fdelete_process, create_process)
(record_child_status_change, handle_child_signal, deliver_child_signal)
(init_process_emacs, syms_of_process):
Assume SIGCHLD is defined.
(parse_signal): Remove.  All uses removed.
(abbr_to_signal): New static function.
(Fsignal_process): Use it to convert signal names to ints.
* src/sysdep.c (sys_suspend) [!DOS_NT]: Use kill (0, ...) rather than
kill (getpgrp (), ...).
(emacs_sigaction_init): Assume SIGCHLD is defined.
(init_signals): Assume SIGALRM, SIGCHLD, SIGHUP, SIGKILL,
SIGPIPE, and SIGQUIT are defined.  Do not worry about SIGCLD any more.
* src/syssignal.h (EMACS_KILLPG): Remove.
All uses replaced by 'kill' with a negative pid.
(SIGCHLD): Remove definition, as we now assume SIGCHLD.
* src/w32proc.c (sys_kill): Support negative pids compatibly with POSIX.

Fixes: debbugs:13026