[oe] [meta-networking] update xl2tpd

[Joe MacDonald]

I started digging into the xl2tpd build error reported by Martin here:

        http://comments.gmane.org/gmane.comp.handhelds.openembedded/56983

There's actually a chain of errors here that seemed to be present for quite
some time but only came to light when the Yocto kernel updated from 3.4 to 3.8.
It also turns out that the mainline xl2tpd project has fixed these, so I
started down the road of cherry-picking fixes back, then opted to dump the old
1.3.1 recipe and go with a git-based approach.

Opinions?

-- 
-Joe.
:wq