Update from Gnulib

Update from Gnulib

This incorporates:
2018-10-05 explicit_bzero: make it possible to namespace
2018-10-04 fcntl: make it possible to namespace
2018-10-01 mkostemp, mkostemps: fix C++ compilation on Mac OS X
2018-09-19 maint: mktime.c now shared with glibc
2018-09-18 file-has-acl: fix test failure on Cygwin 2.9
2018-09-18 gettime: nanotime never existed
* admin/merge-gnulib (AVOIDED_MODULES): Add mkdir.
* doc/misc/texinfo.tex, lib/acl-internal.c, lib/acl-internal.h:
* lib/acl_entries.c, lib/explicit_bzero.c, lib/fcntl.c:
* lib/get-permissions.c, lib/gettime.c, lib/mktime.c:
* lib/set-permissions.c, lib/stdlib.in.h, m4/acl.m4, m4/gettime.m4:
Copy from Gnulib.
* lib/gnulib.mk.in: Regenerate.