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

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

This incorporates:
2020-08-23 intprops: be consistent about +X vs X+0
2020-08-23 intprops: fix INT_MULTIPLY_WRAPV bit-field bug
2020-08-23 verify: Make assume work on bit field expressions
2020-08-23 libc-config: Improve comments
2020-08-22 verify: Do use __builtin_assume on clang
2020-08-22 sig2str: Add more signals
2020-08-21 sigdescr_np: New module
* lib/cdefs.h, lib/intprops.h, lib/sig2str.c, lib/string.in.h:
* lib/verify.h, m4/string_h.m4: Copy from Gnulib.
* lib/gnulib.mk.in: Regenerate.

This incorporates:
2020-08-16 time_rz: remove unused functions
2020-08-16 time_rz: fix issues with mktime_z failures
2020-08-16 nstrftime: Guide inlining also on clang
2020-08-16 intprops: Avoid bogus warning on clang
2020-08-16 libc-config: Enable __REDIRECT macro also on clang
2020-08-16 regex: Use initializer shorthand syntax also with clang
2020-08-16 regex: Use space optimization also with clang
2020-08-16 Use _Static_assert and static_assert when present on clang
2020-08-16 Use 'throw ()' for optimization in C++ mode also on clang
2020-08-16 stdio: Don't break attribute 'scanf' on clang
2020-08-16 Fix "warning: 'format' attribute ...: rpl_printf"
2020-08-16 Fix "warning: attribute declaration must precede definition"
2020-08-16 Fix undesired warnings
2020-08-16 Don't use Autoconf quadrigraphsxo
2020-08-16 Fix quoting of AC_LANG_PROGRAM arguments
2020-08-16 Assume autoconf >= 2.64
2020-08-15 nstrftime: be more predictable about errno
2020-08-15 canonicalize: Fix autoconf test on MSVC/clang
2020-08-15 Support compiling without -loldnames on native Windows
2020-08-14 mktime, mktime-internal: Remove obsolete code
2020-08-14 Assume tzset exists
* lib/c++defs.h, lib/canonicalize-lgpl.c, lib/cdefs.h, lib/dup2.c:
* lib/fcntl.in.h, lib/getopt-cdefs.in.h, lib/intprops.h, lib/md5.h:
* lib/mktime.c, lib/nstrftime.c, lib/open.c, lib/regcomp.c:
* lib/regex_internal.h, lib/stdio.in.h, lib/stdlib.in.h:
* lib/strftime.h, lib/string.in.h, lib/sys_select.in.h:
* lib/sys_stat.in.h, lib/sys_time.in.h, lib/time.in.h, lib/time_rz.c:
* lib/unistd.in.h, lib/verify.h, m4/00gnulib.m4:
* m4/absolute-header.m4, m4/alloca.m4, m4/canonicalize.m4, m4/dup2.m4:
* m4/fchmodat.m4, m4/fcntl.m4, m4/fdopendir.m4, m4/fpending.m4:
* m4/futimens.m4, m4/getdtablesize.m4, m4/getloadavg.m4:
* m4/gnulib-common.m4, m4/include_next.m4, m4/largefile.m4:
* m4/manywarnings.m4, m4/mktime.m4, m4/nstrftime.m4, m4/open-slash.m4:
* m4/pselect.m4, m4/pthread_sigmask.m4, m4/time_h.m4, m4/utimens.m4:
* m4/utimensat.m4, m4/utimes.m4, m4/warnings.m4:
Copy from Gnulib.
* lib/gnulib.mk.in: Regenerate.

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.

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

This incorporates:
2019-11-24 Fix errors in C++ mode on mingw
2019-11-24 time_r: Fix for mingw (regression from 2019-11-16)
2019-11-24 sys_time: Fix errors in C++ mode on mingw
2019-11-22 intprops: INT_MULTIPLY_WRAPV speedup for GCC 8.4+
2019-11-21 Disable many _GL_CXXALIASWARN on non-glibc
2019-11-21 Fix various errors in _GL_CXXALIAS_SYS invocations
2019-11-19 intprops: INT_MULTIPLY_WRAPV speedup for GCC 9.3+
2019-11-18 stdint: Define [u]intptr_t correctly on 64-bit native Windows
2019-11-18 stdint: Fix value of WINT_MAX when we override wint_t
2019-11-18 stdint: Avoid "conflicting types" error on mingw 5.22
2019-11-16 time_r: Fix for mingw
2019-11-06 regex: now back in sync with glibc
* lib/intprops.h, lib/regexec.c, lib/signal.in.h:
* lib/stdint.in.h, lib/stdio.in.h, lib/stdlib.in.h:
* lib/string.in.h, lib/sys_select.in.h, lib/sys_time.in.h:
* lib/time.in.h, lib/unistd.in.h, m4/time_r.m4:
Copy from Gnulib.

This incorporates:
2019-10-23 nstrftime: speed up integer overflow checking
2019-10-23 port better to GCC under macOS
2019-10-15 inttypes: use more-robust test for int range
2019-10-14 update-copyright: use en dashes in .texi ranges
* build-aux/update-copyright, lib/intprops.h, lib/inttypes.in.h:
* lib/nstrftime.c, lib/verify.h:
Copy from Gnulib.

This incorporates:
2019-08-25 intprops.h, verify.h: port better to clang
2019-08-21 New strip-trailing-space option for srclist-update
* .gitattributes: Remove doc/misc/texinfo.tex special case,
which is no longer needed now that Gnulib trims blank-at-eol.
* build-aux/install-sh, doc/misc/texinfo.tex, lib/intprops.h:
* lib/regex_internal.c, lib/verify.h: Copy from Gnulib.

This incorporates:
2019-08-17 intprops: port to Oracle Developer Studio 12.6
2019-08-14 intprops: support uchar, ushort _WRAPV dests
* lib/intprops.h: Copy from Gnulib.