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:
* admin/merge-gnulib (GNULIB_MODULES): Add fsusage.
* doc/emacs/files.texi (Directories): Remove documentation of
now-obsolete directory-free-space-program and
directory-free-space-args.
* etc/NEWS: Mention change.
* etc/PROBLEMS: Slow df is no longer a problem.
* lib/fsusage.c, lib/fsusage.h, m4/fsusage.m4:
New files, copied from Gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lisp/dired.el (dired-free-space-program)
(dired-free-space-args): These aliases are now obsolete.
* lisp/files.el (directory-free-space-program)
(directory-free-space-args): Now obsolete.
(get-free-disk-space): Just call file-system-info instead
of the now-obsolete directory-free-space-program.
* nt/gnulib-cfg.mk (OMIT_GNULIB_MODULE_fsusage): New macro.
* src/fileio.c: Include fsusage.h.
(blocks_to_bytes, Ffile_system_info) [!DOS_NT]: New functions.
(syms_of_fileio) [!DOS_NT]: Defsubr file-system-info.
