* All files with FSF copyright notices: Update copyright dates
	using scripts/update-copyrights.
	* locale/programs/charmap-kw.h: Regenerated.
	* locale/programs/locfile-kw.h: Likewise.

	* All files with FSF copyright notices: Update copyright dates
	using scripts/update-copyrights.
	* locale/programs/charmap-kw.h: Regenerated.
	* locale/programs/locfile-kw.h: Likewise.

Many of the things defined by bits/signum.h are invariant across all
supported operating systems.  This patch factors out all of them to a
new header bits/signum-generic.h, which each bits/signum.h will include
and then override whichever things need adjustment.  Normally that will
mean, at most, adding or changing a few signal numbers.

A user-visible side effect is that the obsolete signal constant SIGUNUSED
(which is an alias for SIGSYS on all platforms that define it) is no
longer exposed by any version of bits/signum.h.

A side effect only relevant to glibc hackers is that _NSIG is now defined
in terms of __SIGRTMAX, instead of the other way around.  This is because
__SIGRTMAX varies from platform to platform, but _NSIG==__SIGRTMAX+1 is
true universally.  If your platform doesn't support realtime signals,
leave __SIGRTMAX equal to __SIGRTMIN.

I also added a Linux-specific test to make sure that our signal constants
match the ones in <asm/signal.h>, since we can't use that header (it's
not even vaguely namespace-clean).

	* bits/signum-generic.h: Renamed from bits/signum.h.
	Add proper multiple include guard and misuse check.
	Define __SIGRTMIN = __SIGRTMAX = 32, and define _NSIG = __SIGRTMAX+1.
	Move definition of SIGIO to "archaic names for compatibility" section.
	* bits/signum.h: New file which just includes bits/signum-generic.h.
	* sysdeps/unix/bsd/bits/signum.h
	* sysdeps/unix/sysv/linux/bits/signum.h
	* sysdeps/unix/sysv/linux/alpha/bits/signum.h
	* sysdeps/unix/sysv/linux/hppa/bits/signum.h
	* sysdeps/unix/sysv/linux/mips/bits/signum.h
	* sysdeps/unix/sysv/linux/sparc/bits/signum.h
	Just include <bits/signum-generic.h> and then add or adjust
	signal constants.  Do not define SIGUNUSED, SIGRTMIN, or SIGRTMAX.

	* signal/Makefile: Install bits/signum-generic.h.
	* signal/signal.h: Define SIGRTMIN and SIGRTMAX here.

	* sysdeps/generic/siglist.h: SIGSYS and SIGWINCH are
	universal.  Prefer SIGPOLL to SIGIO. Simplify #ifdeffage.

	* sysdeps/unix/sysv/linux/tst-signal-numbers.sh: New test.
	* sysdeps/unix/sysv/linux/Makefile: Run it.

Various bits/signum.h headers define SIG_HOLD if __USE_UNIX98.  That
should be __USE_XOPEN, as this macro is in XPG4.  This patch fixes the
conditionals accordingly.  Because of other header bugs, this does not
allow any XFAILs to be removed (however, the XPG4/signal.h/conform
XFAIL only depends on a few such straightforward header bugs, not on
the more complicated to fix ucontext_t issues, as ucontext_t isn't
included in signal.h in XPG4).

Tested for x86_64.

	[BZ #21538]
	* bits/signum.h (SIG_HOLD): Define if [__USE_XOPEN], not
	[__USE_UNIX98].
	* sysdeps/unix/bsd/bits/signum.h (SIG_HOLD): Likewise.
	* sysdeps/unix/sysv/linux/alpha/bits/signum.h (SIG_HOLD):
	Likewise.
	* sysdeps/unix/sysv/linux/bits/signum.h (SIG_HOLD): Likewise.
	* sysdeps/unix/sysv/linux/hppa/bits/signum.h (SIG_HOLD): Likewise.
	* sysdeps/unix/sysv/linux/mips/bits/signum.h (SIG_HOLD): Likewise.
	* sysdeps/unix/sysv/linux/sparc/bits/signum.h (SIG_HOLD):
	Likewise.