Merge from gnulib

Merge from gnulib

This incorporates:
2017-04-30 strftime-fixes: New module
2017-04-30 mktime: Work around TZ problem on native Windows
2017-04-30 ctime, localtime: New modules
2017-04-30 gettimeofday: Provide higher resolution on native Windows
2017-04-29 utime-h: Modernize handling of 'struct utimbuf'
2017-04-29 Make use of module 'utime-h'
2017-04-30 Fix a few typos
* admin/merge-gnulib (AVOIDED_MODULES): Avoid utime-h, too.
* lib/gettimeofday.c, lib/mktime.c, lib/time.in.h, lib/utimens.c:
* m4/gettimeofday.m4, m4/include_next.m4, m4/mktime.m4:
* m4/strftime.m4, m4/time_h.m4, m4/timegm.m4, m4/utimens.m4:
Copy from gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.