afs_FindService should handle iana portnames

afs_FindService should handle iana portnames

right now we compare against /etc/services, and a hardcoded array.
but since there's no guarantee /etc/services will be useful, this
can mean inconsistent behavior. hardcode the iana names in the table,
and take the internal structure used private at the same time.

LICENSE BSD

Reviewed-on: http://gerrit.openafs.org/577
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>