nfs-utils: convert rpc.nfsd to use xlog()

nfs-utils: convert rpc.nfsd to use xlog()

...and add --debug and --syslog options.

With the switch to xlog(), it becomes trivial to add debug messages, so
add an option to turn them on when requested.

Also, rpc.nfsd isn't a proper daemon per-se, so it makes more sense to
log errors to stderr where possible. Usually init scripts take care of
redirecting stderr output to syslog anyway.

For those that don't, add a --syslog option that forces all output to go
to syslog instead. Note that even with this option, errors encountered
during option processing will still go to stderr.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve Dickson <steved@redhat.com>