This incorporates:
2020-01-10 fix major regression from 2020-01-04
2020-01-05 tests: avoid GCC over-optimization
2020-01-04 fix AC_CHECK_DECL so it deactivates clang's built-ins
2020-01-03 getopt-posix: fix compilation failure in testdirs
2020-01-03 doc: mention the 64-bit inode number problem
2020-01-02 wchar: make the HP-UX workaround work on HP-UX 11.31
* build-aux/config.guess, build-aux/config.sub, lib/inttypes.in.h:
* lib/stdlib.in.h, lib/unistd.in.h, m4/00gnulib.m4, m4/largefile.m4:
* m4/unistd_h.m4: Copy from Gnulib
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.

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:
2019-12-06 nstrftime: better width support for %N, %z
2019-12-03 Avoid hassles caused by [[noreturn]] in C++
2019-12-02 Fix mistakes in --enable-threads=isoc fixes from 2019-12-01
* admin/merge-gnulib (AVOIDED_MODULES): Avoid pthread-h.
* lib/_Noreturn.h, lib/nstrftime.c, m4/gnulib-common.m4:
* m4/timer_time.m4:
Copy from Gnulib.
* lib/gnulib.mk.in: Regenerate.

etags had undefined behavior if input files, lines, tags, etc.,
had more than INT_MAX bytes.  Clean up the usage of integer types
to fix the overflow errors I found.
* admin/merge-gnulib (GNULIB_MODULES): Add mempcpy.
* lib-src/etags.c: Include inttypes.h, intprops.h.
(memcpyz): New function.  Use it to simplify several occurrences
of memcpy followed by storing a trailing '\0'.
(xnew): Use xnmalloc, to catch overflow on integer multiplication.
(xrnew): Change last arg to multiplier.  The type is not needed.
All callers changed.
(node, lineno, charno, linecharno, invalidcharno, make_tag):
(pfnote, add_node, number_len, C_symtype, lbz, Makefile_targets)
(readline):
Use intmax_t for line numbers and character positions, instead of
int or long.
(linebuffer, make_tag, pfnote, total_size_of_entries, put_entry)
(in_word_set, C_symtype, token, cstack, pushclass_above):
(popclass_above, write_classname, consider_token, C_entries)
(Ruby_functions, Makefile_targets, Lua_functions, TeX_commands)
(TeX_decode_env, erlang_func, erlang_attribute, erlang_atom)
(substitute, regex_tag_multiline, nocase_tail, readline_interval)
(readline, savenstr, concat, etags_getcwd, relative_filename)
(linebuffer_setlen):
Use ptrdiff_t for object sizes, instead of int or long or unsigned
or size_t.
(write_classname, C_entries):
Avoid sprintf, as the result could exceed INT_MAX bytes
and then behavior goes haywire.
(main): Use int, instead of unsigned, for argv counts.
(get_language_from_filename): Use bool for boolean.
(Ruby_functions): Prefer strcpy to memcpy when copying "=".
(linebuffer_setlen): Use ‘if’ instead of ‘while’.
(memory_full, xnmalloc, xnrealloc): New functions.
(xmalloc): Use memory_full, and take a ptrdiff_t instead of a size_t.
(xrealloc): Remove; no longer needed.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lib/mempcpy.c, m4/mempcpy.m4: New files, copied from Gnulib.

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:
2019-10-24 timespec-add, timespec-sub: simplify
* lib/timespec-add.c, lib/timespec-sub.c:
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:
2019-10-11 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 mostly changes http: to https: in URLs.  It also updates
some URLs that have moved, removes some URLs that no longer
work, recommends against using procmail (procmail.org no
longer works), and removes some mentions of the
no-longer-existing Gmane, LPF and VTW.
It doesn't update all URLs, just the ones I had time for.
* GNUmakefile (help):
* admin/admin.el (manual-doctype-string):
* admin/charsets/Makefile.in (${charsetdir}/ALTERNATIVNYJ.map):
* admin/charsets/mapconv:
* lisp/net/soap-client.el (soap-create-envelope):
* lisp/org/org.el (org-doi-server-url):
* lisp/textmodes/bibtex.el (bibtex-generate-url-list):
Prefer https: to http: un URLs.