1. make fileops const
2. add 2 new negative errno's to `officially' support the cloning hack:
- EDUPFD (used to overload ENODEV)
- EMOVEFD (used to overload ENXIO)
3. Created an fdclone() function to encapsulate the operations needed for
EMOVEFD, and made all cloners use it.
4. Centralize the local noop/badop fileops functions to:
fnullop_fcntl, fnullop_poll, fnullop_kqfilter, fbadop_stat
the code that `knows' about /dev/[pt]tyXX names (the BSD ptys) into a separate
file. Make an interface to be used by the tty creating provider. The code
to enable old PTY searching via ptm is enabled via COMPAT_BSDPTY, and it
is turned on by default on all kernels that have compatibility options enabled.