* m4/pthread_sigmask.m4 (gl_FUNC_PTHREAD_SIGMASK): Test for the
FreeBSD, HP-UX, Solaris bug.
(gl_PREREQ_PTHREAD_SIGMASK): New macro.
* lib/pthread_sigmask.c: Include <stddef.h>.
(pthread_sigmask): If HAVE_PTHREAD_SIGMASK, define as a wrapper around
the system's pthread_sigmask function.
* modules/pthread_sigmask (configure.ac): Invoke
gl_PREREQ_PTHREAD_SIGMASK.
* doc/posix-functions/pthread_sigmask.texi: Mention bug on FreeBSD,
HP-UX, Solaris.
* lib/signal.in.h (pthread_sigmask): Override if
REPLACE_PTHREAD_SIGMASK is 1.
* m4/signal_h.m4 (gl_SIGNAL_H_DEFAULTS): Initialize
REPLACE_PTHREAD_SIGMASK.
* m4/pthread_sigmask.m4 (gl_FUNC_PTHREAD_SIGMASK): Set also
REPLACE_PTHREAD_SIGMASK. Set and substitute LIB_PTHREAD_SIGMASK.
* modules/signal (Makefile.am): Substitute REPLACE_PTHREAD_SIGMASK.
* modules/pthread_sigmask (Depends-on, configure.ac): Update condition.
(Link): Set to $(LIB_PTHREAD_SIGMASK), not $(LIBMULTITHREAD).
* lib/signal.in.h: In two special conditions, just do an #include_next.
(pthread_sigmask): Test HAVE_PTHREAD_SIGMASK, not REPLACE_PTHREAD_MASK.
Invoke _GL_CXXALIAS_SYS and _GL_CXXALIASWARN.
* m4/signal_h.m4 (gl_SIGNAL_H_DEFAULTS): Initialize
HAVE_PTHREAD_SIGMASK, not REPLACE_PTHREAD_MASK.
* m4/pthread_sigmask.m4 (gl_PTHREAD_SIGMASK): Set HAVE_PTHREAD_SIGMASK,
not REPLACE_PTHREAD_MASK.
* modules/signal (Makefile.am): Substitute HAVE_PTHREAD_SIGMASK,
not REPLACE_PTHREAD_MASK.
* modules/pthread_sigmask (Depends-on, configure.ac): Update condition.
* MODULES.html.sh (Support for systems lacking POSIX:2008): Add it.
* doc/posix-functions/pthread_sigmask.texi: Document new module.
* lib/signal.in.h (pthread_sigmask): Arrange for replacement.
This is done only as a macro; I don't know how well that'll
work for C++. Move <sys/types.h> include before the include_next,
to avoid mishap on Solaris.
* m4/signal_h.m4 (gl_SIGNAL_H, gl_SIGNAL_H_DEFAULTS): Check for it.
* modules/signal (Makefile.am): Substitute the check's results.
* modules/pthread_sigmask, m4/pthread_sigmask.m4: New files.