This incorporates:
2020-05-11 careadlinkat: fix GCC 10 workaround
2020-05-10 careadlinkat: limit GCC workaround
2020-05-10 attribute: clarify list of attributes
2020-05-10 string: fix compilation error in C++ mode
2020-05-09 manywarnings: port to GCC 10.1
2020-05-09 careadlinkat: pacify -Wreturn-local-addr
2020-05-09 attribute: remove ATTRIBUTE_DEPRECATED
2020-05-09 attribute: Add comments
* lib/attribute.h, lib/careadlinkat.c, lib/string.in.h:
* lib/warn-on-use.h, m4/manywarnings.m4: Copy from Gnulib.

This incorporates:
2020-05-09 stdio: don't redefine _GL_ATTRIBUTE_FORMAT
2020-05-09 dirent, stdlib, string: don't redefine _GL_ATTRIBUTE_PURE
2020-05-08 limits-h: define LONG_BIT correctly on Haiku/x86_64
2020-05-08 ignore-value tests: use module 'attribute'
2020-05-06 attribute: minor style fixes
* build-aux/config.sub, doc/misc/texinfo.tex, lib/attribute.h:
* lib/dirent.in.h, lib/limits.in.h, lib/stdio.in.h, lib/stdlib.in.h:
* lib/string.in.h, m4/gnulib-common.m4:
Copy from Gnulib.

This incorporates:
2020-05-03 attribute: new module
2020-04-13 explicit_bzero: improve code style
2020-04-13 explicit_bzero: On native Windows, use SecureZeroMemory
2020-04-13 explicit_bzero: use memset_s() when available
2020-04-04 maint: remove a stray inter-word space
* build-aux/config.guess, build-aux/config.sub:
* build-aux/gitlog-to-changelog, build-aux/update-copyright:
* doc/misc/texinfo.tex, lib/explicit_bzero.c, lib/ieee754.in.h:
* lib/nstrftime.c, m4/explicit_bzero.m4, m4/gnulib-common.m4:
Copy from Gnulib.
* lib/attribute.h: New file, copied from Gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.

05089a4d65 (origin/emacs-27) Tweak wording re constant variables
a1040861f1 Tweak setcar-related wording
751510f865 * lisp/image-mode.el: Add prefix key 's' and reduce depend...
9261a219ec * doc/emacs/windows.texi (Window Convenience): Decribe mor...
e1d42da0d6 Fix mutability glitches reported by Drew Adams
5805df74f5 Improve mutability doc
dca35b31d0 Improve mutability documentation
81e7d7f111 Document that quoting yields constants
5734339f40 * doc/lispref/keymaps.texi (Extended Menu Items, Easy Menu...
14a570afae Remove #' and function quoting from lambda forms in manual
d5ec18c66b * src/regex-emacs.c (re_match_2_internal): Rework comment ...
4df8a61117 Add new node "Image Mode" to Emacs Manual.
d7d5ee6c57 ; Fix a typo in cmdargs.texi (bug#40701)
5e9db48fbe * doc/lispref/display.texi (Customizing Bitmaps): Fix typo.
eebfb72c90 Document constant vs mutable objects better
6c187ed6b0 Improve documentation of 'sort-lines'
52288f4b66 Mention 'spam-stat-process-directory-age' in the documenta...
067b070598 ; Fix some typos and doc issues (bug#40695)

# Conflicts:
#	etc/NEWS

Code is supposed to use the filename module now.
* admin/merge-gnulib (GNULIB_MODULES): Replace dosname with filename.
* lib/dosname.h: Remove this forwarding stub.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lib-src/emacsclient.c, src/fileio.c:
Include filename.h instead of dosname.h.

This incorporates:
2020-03-28 Use module 'filename' instead of module 'dosname'
2020-03-28 dosname: Redirect to 'filename'
* lib/at-func.c, lib/canonicalize-lgpl.c, lib/dosname.h:
Copy from Gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lib/filename.h: New file, copied from Gnulib.

This incorporates:
2020-03-25 getopt-posix: port __GETOPT_PREFIX to macOS
2020-03-22 acl-permissions: Improve autoconf macro
* lib/getopt-pfx-core.h, m4/acl.m4: Copy from Gnulib.

This is a companion to the recent set-file-modes patch.
It adds support for a ‘nofollow’ flag to set-file-times (Bug#39773).
Like the set-file-modes patch, it needs work in the w32 port.
* admin/merge-gnulib (GNULIB_MODULES): Add futimens, utimensat.
Remove utimens.
* doc/lispref/files.texi (Changing Files):
* etc/NEWS: Mention the change.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lisp/files.el (copy-directory):
* lisp/gnus/gnus-cloud.el (gnus-cloud-replace-file):
* lisp/net/tramp-adb.el (tramp-adb-handle-copy-file):
* lisp/net/tramp-smb.el (tramp-smb-handle-copy-file):
* lisp/tar-mode.el (tar-copy):
* test/lisp/filenotify-tests.el (file-notify-test03-events):
* test/lisp/files-tests.el:
(files-tests-file-name-non-special-set-file-times):
* test/lisp/net/tramp-tests.el (tramp-test22-file-times):
When setting file times, avoid following symbolic links
when the file is not supposed to be a symbolic link.
* lib/futimens.c, lib/utimensat.c, m4/futimens.m4, m4/utimensat.m4:
New files, copied from Gnulib.
* lisp/gnus/gnus-cloud.el (gnus-cloud-replace-file):
When creating a file that is not supposed to exist already,
use the excl flag to check this.
* lisp/net/tramp-adb.el (tramp-adb-handle-set-file-times):
* lisp/net/tramp-sh.el (tramp-sh-handle-set-file-times):
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-handle-set-file-times):
Accept an optional FLAG arg that is currently ignored,
and add a FIXME comment for it.
* lisp/net/tramp-gvfs.el (tramp-gvfs-handle-set-file-times):
* src/fileio.c (Fset_file_times):
Support an optional FLAG arg.
* src/fileio.c (Fcopy_file): Use futimens instead of set_file_times,
as it’s simpler and is a POSIX API.
* src/sysdep.c (set_file_times): Move from here ...
* src/w32.c (set_file_times): ... to here, and make it static,
since it is now used only in w32.c.  Presumably w32.c should also
add support for futimens and utimensat (the POSIX APIs, which
Emacs now uses) and it can remove fdutimens (the Gnulib API,
which Emacs no longer uses).

This incorporates:
2020-03-07 open, openat: port to (O_RDWR | O_RDONLY) != 0
* lib/open.c: Copy from Gnulib.