* 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
