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
2017-01-30 Port to PGI 16.10 x86-64
2017-01-20 time_rz: fix comment typo
2017-01-14 strftime: %z is -00 if unknown
This incorporates:
* doc/misc/texinfo.tex, lib/c-ctype.h, lib/strftime.c:
* lib/time-internal.h, lib/verify.h:
Copy from gnulib.
This incorporates:
2015-07-27 time_rz: port better to MinGW
2015-07-27 time: port __need_time_t to MinGW
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* lib/strftime.c, lib/time.in.h, lib/time_rz.c: Copy from gnulib.
* lib/time-internal.h: New file, from gnulib.