Update from Gnulib

Update from Gnulib

This incorporates:
2018-05-21 crypto: omit stream ops Emacs doesn’t need
2018-05-13 truncate: Fix compilation error on Android
2018-05-13 imaxdiv: Fix compilation error on Android
2018-05-13 Support selective inclusion of recent mingw.org headers
2018-05-13 Add cross-compilation guesses for Linux systems sans glibc
2018-05-13 stdioext: Fix compilation errors with newer Android headers
2018-05-07 af_alg: Pacify --enable-gcc-warnings
2018-05-06 af_alg: Fix bug with streams that are not at position 0
2018-05-06 Followup to 'af_alg: New module'
2018-05-05 crypto/{md5,sha1,sha256,sha512}: simplify
2018-05-05 af_alg: New module
2018-05-05 af_alg: Improve function signature
2018-04-28 md5sum: Use AF_ALG when available
2018-04-28 sha512sum: Use AF_ALG when available
2018-04-28 sha256sum: Use AF_ALG when available
2018-04-28 sha1sum: Use AF_ALG when available
2018-05-05 all: Replace more http URLs by https URLs
2018-05-03 maint: port more modules to GCC 8
2018-05-03 Simplify code; drop support for Borland C++ on Windows
* admin/merge-gnulib (GNULIB_MODULES): Use crypto/md5-buffer
rather than crypto/md5, since Emacs doesn’t use the stream
operations that in recent Gnulib pull in other stuff Emacs doesn’t
need.  Similarly for crypto/sha1-buffer, crypto/sha256-buffer,
crypto/sha512-buffer.
* build-aux/config.guess, build-aux/config.sub, lib/dosname.h:
* lib/dup2.c, lib/errno.in.h, lib/euidaccess.c, lib/fcntl.c:
* lib/fcntl.in.h, lib/fpending.c, lib/fsync.c, lib/getdtablesize.c:
* lib/getopt.c, lib/gettimeofday.c, lib/inttypes.in.h, lib/md5.c:
* lib/md5.h, lib/open.c, lib/pipe2.c, lib/putenv.c, lib/sha1.c:
* lib/sha1.h, lib/sha256.c, lib/sha256.h, lib/sha512.c:
* lib/sha512.h, lib/stat-time.h, lib/stdio-impl.h, lib/stdio.in.h:
* lib/stdlib.in.h, lib/sys_stat.in.h, lib/sys_types.in.h:
* lib/timespec.h, lib/unistd.in.h, lib/utimens.c, m4/c-strtod.m4:
* m4/gnulib-common.m4, m4/inttypes.m4, m4/lstat.m4, m4/nocrash.m4:
* m4/pselect.m4, m4/readlink.m4, m4/stdio_h.m4, m4/symlink.m4:
* m4/unistd_h.m4, m4/utimens.m4:
Copy from Gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.