* libc/posix/popen.c (popen): The 2006-08-22 change to use
FD_CLOEXEC disagrees with other implementations; instead, use
pidlist to work even when fcntl is not available. Meanwhile,
support the 'e' modifier to set CLOEXEC, as in glibc. Drop
cygwin-specific code, now that cygwin has its own version.
* libc/posix/Makefile.am (CHEWOUT_FILES): Document popen.
* libc/posix/posix.tex: New file.