libwrap's *_severity references should be something other than NODIRECT
When reviewing a separate change, I noticed that we use NODIRECT to deal with libwrap's references to allow_severity/deny_severity.
NODIRECT is the wrong thing for this, it should be either EXTERN or PARENT. I'm just not sure which. Probably EXTERN (the difference is that PARENT allows a direct binding to be established, EXTERN doesn't).
I'm not sure there's any particular motivation to gather the energy to care about libwrap enough to test a fix for this, but I wanted it recorded.