svcauth_null_accept() and svcauth_unix_accept() are currently hard-wired to
check the source ip address on an incoming request against the export table,
which make sense for nfsd but not necessarily for other rpc-based services.

So instead we have the accept() method call a program-specific
pg_authenticate() method.  We also move the call to this method into
svc_process instead of calling it from the flavor-specific accept() routines.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>