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This incorporates:
2017-07-13 Improve cross-compilation guesses for native Windows
2017-07-11 More systematic m4 quoting and indentation
2017-07-10 Make sure $host and $host_os are defined when used
2017-07-03 stdioext: Port to OpenVMS
2017-06-24 xalloc-oversized: port to icc
* doc/misc/texinfo.tex, lib/fpending.c, lib/stdio-impl.h:
* lib/xalloc-oversized.h, m4/dirfd.m4, m4/gettimeofday.m4:
* m4/lstat.m4, m4/mktime.m4, m4/pselect.m4, m4/putenv.m4:
* m4/stdint.m4, m4/strtoimax.m4, m4/utimes.m4:
Copy from Gnulib.