Run "TZ=UTC0 admin/update-copyright $(git ls-files)".

This incorporates:
2019-10-11 Simplify and regularize regex use of ‘assert’
2019-10-09 regex: omit debug assignment when not debugging
2019-10-09 regex: tell compiler there’s at most 256 arcs out
2019-10-09 regex: simplify by assuming C99
2019-10-09 regex: avoid copying of uninitialized storage
2019-09-29 fbufmode: Fix compilation error on glibc >= 2.28 systems
2019-09-28 Update comments that refer to POSIX
2019-09-23 Update URLs and associated text
* doc/misc/texinfo.tex, lib/open.c, lib/regcomp.c:
* lib/regex_internal.c, lib/regex_internal.h, lib/regexec.c:
* lib/stdio-impl.h:
Copy from Gnulib.

This incorporates:
2019-03-23 Support cross-compilation to musl libc
2019-03-23 noreturn: In C++ mode with clang, use _Noreturn as fallback
2019-03-22 _Noreturn: beware of C's _Noreturn in C++ pre C++11
2019-03-19 Help making signal handlers more reliable
2019-03-18 _Noreturn: clang and MSVC do support [[noreturn]] in C++11
2019-03-17 _Noreturn: GCC 4.7 does not support [[noreturn]] in C++11
2019-03-14 all: Update URLs to msdn.microsoft.com
* doc/misc/texinfo.tex, lib/_Noreturn.h, lib/gettimeofday.c:
* lib/mktime.c, lib/regcomp.c, lib/regexec.c, lib/stat-time.h:
* lib/utimens.c, m4/fdopendir.m4, m4/getgroups.m4:
* m4/gettimeofday.m4, m4/gnulib-common.m4, m4/putenv.m4, m4/utimes.m4:
Update from gnulib.

This incorporates mostly just copyright-year changes, plus
recent minor updates from glibc for the non-Emacs regular
expression code.

* build-aux/config.guess, lib/regcomp.c, lib/regex.c:
* lib/regex_internal.h, lib/regexec.c: Copy from Gnulib.

This syncs recent refactorings from glibc, and incorporates:
2018-10-15 libc-config: merge from glibc
2018-10-15 regex: depend on libc-config
* .gitignore: Do not ignore m4/_*.m4.
* lib/cdefs.h: New file, copied from Gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lib/libc-config.h, m4/__inline.m4: New files, copied from Gnulib.
* lib/regcomp.c, lib/regex.c, lib/regex_internal.c:
* lib/regex_internal.h, lib/regexec.c:
Copy from glibc via Gnulib.

This incorporates:
2018-08-11 verify: port 'assume' to traditional tools
* build-aux/config.sub, lib/regcomp.c, lib/verify.h:
Copy from Gnulib.
* lib/gnulib.mk.in: Regenerate.

Emacs regular expressions forked from everyone else long ago.
This makes it official and should allow simplification later.
etags.c now uses the glibc regex API, falling back on a
Gnulib-supplied substitute lib/regex.c if necessary.
Emacs proper now uses its own regular expression module.
Although this patch may look dauntingly large, most of it
was generated automatically by admin/merge-gnulib
and contains an exact copy of the glibc regex source,
and the by-hand changes do not grow the Emacs source code.
* admin/merge-gnulib (GNULIB_MODULES): Add regex.
(AVOIDED_MODULES): Add btowc, langinfo, lock, mbrtowc, mbsinit,
nl_langinfo, wchar, wcrtomb, wctype-h.
* lib-src/Makefile.in (regex-emacs.o): Remove; Gnulib does it now.
(etags_deps, etags_libs): Remove regex-emacs.o.
* lib-src/etags.c: Go back to including regex.h.
(add_regex): Use unsigned char translation array,
since glibc regex requires that.
* lib/Makefile.in (not_emacs_OBJECTS, for_emacs_OBJECTS): New macros.
(libegnu_a_OBJECTS): Use them, to avoid building e-regex.o.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lib/regcomp.c, lib/regex.c, lib/regex.h, lib/regex_internal.c:
* lib/regex_internal.h, lib/regexec.c, m4/builtin-expect.m4:
* m4/eealloc.m4, m4/glibc21.m4, m4/mbstate_t.m4, m4/regex.m4:
New files, copied from Gnulib.
* src/regex-emacs.h, src/conf_post.h:
(RE_TRANSLATE_TYPE, RE_TRANSLATE, RE_TRANSLATE_P):
Move from src/conf_post.h to src/regex-emacs.h,
so that they don’t interfere with compiling lib/regex.c.