Run "TZ=UTC0 admin/update-copyright".

All changes in this commit are autogenerated by running
admin/merge-gnulib.

This incorporates:
2020-09-05 verify: avoid __builtin_assume
2020-08-30 strerrorname_np: New module
2020-08-26 include_next, stdint, time_rz: Change configure message
* lib/gnulib.mk.in: Regenerate.
* lib/string.in.h, lib/verify.h, m4/include_next.m4, m4/stdint.m4:
* m4/string_h.m4, m4/time_rz.m4: Copy from Gnulib.

This incorporates:
2020-08-11 Use expression statements also on clang
2020-08-10 Use many __attribute__s with clang
2020-08-09 Use attribute __aligned__ with clang
2020-08-09 Use __alignof__ with clang
2020-08-09 ignore-value: Simplify on clang
2020-08-09 Use __typeof__ with clang
2020-08-09 intprops: Fix typo in comment
2020-08-09 Silence warnings from clang 10 with -Wimplicit-fallthrough
2020-08-09 count-one-bits: Use __builtin_popcount{,l,ll} on clang
2020-08-09 string: Fix build error in C++ mode with clang
2020-08-09 Add ability to emit user-defined diagnostics with clang
2020-08-07 alloca: No need to compile alloca.c with clang
2020-08-06 Use __builtin_assume with clang
* lib/alloca.in.h, lib/arg-nonnull.h, lib/c++defs.h, lib/cdefs.h:
* lib/count-one-bits.h, lib/dirent.in.h, lib/ignore-value.h:
* lib/intprops.h, lib/malloca.h, lib/regex_internal.h:
* lib/stdalign.in.h, lib/stddef.in.h, lib/stdio.in.h:
* lib/stdlib.in.h, lib/string.in.h, lib/verify.h, lib/warn-on-use.h:
* m4/gnulib-common.m4, m4/stddef_h.m4, m4/stdint.m4:
Copy from Gnulib.

This incorporates:
2019-12-23 mktime, nstrftime: tweak division performance
2019-12-22 count-leading-zeros: assume 'long long'
2019-12-22 count-one-bits: assume 'long long'
2019-12-22 count-trailing-zeros: assume 'long long'
2019-12-12 inttypes-incomplete: assume 'long long'
2019-12-22 malloca: assume 'long long'
2019-12-22 stdint: assume 'long long'
2019-12-22 strtoll, strtoimax, strtoumax: assume 'long long'
2019-12-22 prefer lib_SOURCES to unconditional AC_LIBOBJ
2019-12-19 nstrftime: avoid a shadowing warning
2019-12-18 improve port of AC_C_RESTRICT to Oracle C++
2019-12-12 stdalign: port to xlclang 16.01
2019-12-11 stddef, unistd: fix compilation error in C++ mode on MSVC
2019-12-08 fix compilation errors in C++ mode on Haiku
2019-12-08 fix compilation errors in 32-bit C++ mode on HP-UX 11/ia64
2019-12-08 fix compilation error in C++ mode on OpenBSD
* build-aux/config.guess, doc/misc/texinfo.tex:
* lib/count-leading-zeros.h, lib/count-one-bits.h:
* lib/count-trailing-zeros.h, lib/inttypes.in.h, lib/malloca.h:
* lib/mktime.c, lib/nstrftime.c, lib/signal.in.h, lib/stdalign.in.h:
* lib/stddef.in.h, lib/stdint.in.h, lib/stdio.in.h, lib/stdlib.in.h:
* lib/strtoimax.c, lib/unistd.in.h, m4/gnulib-common.m4:
* m4/inttypes.m4, m4/largefile.m4, m4/malloca.m4, m4/strtoimax.m4:
* m4/strtoll.m4:
Copy from Gnulib.  Also, change copyright notices in some other
Gnulib-copied files to exactly match Gnulib, as Gnulib updated
them in a trivially different way.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.

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

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

This incorporates:
2018-11-03 nstrftime: simplify test for mktime failure
2018-11-02 gnulib-common.m4: port _Noreturn to C++
2018-10-22 std-gnu11: Support Autoconf versions < 2.64
2018-10-22 Assume Autoconf >= 2.63
2018-10-16 Remove support for Ultrix
2018-10-16 getloadavg: Remove support for ConvexOS
2018-10-16 getloadavg: Remove support for Sony NEWS
2018-10-16 Remove support for Dynix/ptx
2018-10-16 fsusage: Remove support for AIX 3
2018-10-16 fsusage, stat-size, getloadavg: Remove support for AIX PS/2
2018-10-16 getloadavg: Remove support for HP-UX on m68k
2018-10-16 fsusage, mountlist: Remove support for DolphinOS
2018-10-16 getloadavg: Remove support for Alliant FX/2800
2018-10-16 getloadavg: Remove support for tek4300
2018-10-16 getloadavg: Remove support for Ardent
* build-aux/config.guess, build-aux/config.sub, lib/_Noreturn.h:
* lib/fsusage.c, lib/getgroups.c, lib/getloadavg.c:
* lib/nstrftime.c, lib/time.in.h, m4/errno_h.m4:
* m4/fsusage.m4, m4/getgroups.m4, m4/gnulib-common.m4, m4/longlong.m4:
* m4/std-gnu11.m4, m4/stdint.m4:
Copy from Gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate:

* build-aux/config.sub, lib/intprops.h, lib/regex_internal.c:
* lib/regex_internal.h, lib/unistd.in.h, m4/limits-h.m4:
* m4/stdint.m4, m4/unistd_h.m4:
Copy from Gnulib.
* lib/gnulib.mk.in: Regenerate.

This incorporates:
2018-01-01 maint: Run 'make update-copyright'
2017-12-29 Add cross-compilation results for GNU/Hurd.
2017-12-12 explicit_bzero: port to macOS + Clang 9.0.0