create fd, stdin, stdout, stderr symlinks in /dev

The kernel's Documentation/devices.txt says that these symlinks should
exist in /dev (they are listed in the "Compulsory" section). I'm not
currently adding nfsd and X0R since they are required for iBCS, but
they can be easily added to the array later if need be.

Signed-off-by: Dwight Engen <dwight.engen@oracle.com>
Acked-by: Michael H. Warfield <mhw@WittsEnd.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>