This incorporates:
2015-10-13 binary-io, u64, unistd: port to strict C
2015-09-26 c-ctype: do not worry about EBCDIC + char signed
2015-09-25 c-ctype: port better to z/OS EBCDIC
2015-09-25 gnulib-common.m4: fix gl_PROG_AR_RANLIB/AM_PROG_AR clash
* doc/misc/texinfo.tex, lib/binary-io.c, lib/c-ctype.h, lib/u64.c:
* lib/unistd.c, m4/gnulib-common.m4, m4/gnulib-comp.m4:
Copy from gnulib.
* lib/binary-io.c, lib/binary-io.h: New files.
Merge from gnulib, incorporating:
2013-07-09 accept4, dup3, pipe2: port to Cygwin
* lib/pipe2.c: Update from gnulib, as part of this merge.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
Fixes: debbugs:14821
