glibc socket to flush the nscd tables. This comes from the RedHat
patch shadow-4.0.16-nscd.c.
* lib/commonio.c: Forbid inheritance of the passwd and group files
to the spawed processes (like nscd). This comes from the RedHat
patch shadow-4.0.17-notInheritFd.patch.
* lib/nscd.h: Update header.