pkgbase: Put ppp in it's own package

[manu]

Summary

ppp uses libalias modules which now belong in the natd package.
Avoid bringing a dependancy on natd for the utilities package.

[emaste]

OK, although IMO we could just put ppp and natd in the same package - I just don't know what we should name it then.

[manu]

In D27711#624261, @emaste wrote:

OK, although IMO we could just put ppp and natd in the same package - I just don't know what we should name it then.

Exactly the reason why I've put it on it's own package :P