Update from Gnulib

Update from Gnulib

This incorporates:
2019-09-22 Update some URLs
2019-09-15 fcntl-h: fix compilation error of creat.c on MSVC
2019-09-15 creat: new module
2019-09-15 access: new module
2019-09-09 Add option to assume best, not worst, when cross-compiling.
* build-aux/config.guess, build-aux/config.sub, doc/misc/texinfo.tex:
* lib/careadlinkat.c, lib/careadlinkat.h, lib/count-leading-zeros.h:
* lib/count-trailing-zeros.h, lib/diffseq.h, lib/fcntl.in.h:
* lib/ftoastr.c, lib/get-permissions.c:
* lib/ieee754.in.h, lib/inttypes.in.h, lib/mktime.c, lib/open.c:
* lib/pathmax.h, lib/pipe2.c, lib/stddef.in.h, lib/stdint.in.h:
* lib/stdlib.in.h, lib/str-two-way.h, lib/string.in.h, lib/time.in.h:
* lib/timegm.c, lib/unistd.in.h, m4/canonicalize.m4:
* m4/extern-inline.m4, m4/fcntl_h.m4, m4/fdopendir.m4:
* m4/getgroups.m4, m4/getopt.m4, m4/gettimeofday.m4:
* m4/gnulib-common.m4, m4/largefile.m4:
* m4/lstat.m4, m4/memmem.m4, m4/mktime.m4, m4/nocrash.m4, m4/open.m4:
* m4/pselect.m4, m4/putenv.m4, m4/readlink.m4, m4/regex.m4:
* m4/symlink.m4, m4/unistd_h.m4, m4/utimens.m4, m4/utimes.m4:
Copy from Gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* m4/open-slash.m4: New file, copied from Gnulib.