### Please describe the problem.
Hi!
I just tried to build git-annex through cabal on OpenBSD and encountered some issues.

First I had to install a certain commit of network-info that fixes some compile-time errors (https://github.com/jystic/network-info/issues/6)
Then I had to disable WebDAV in git-annex because DAV wouldn't build (I don't use webdav anyway)

After this git-annex still failed to build, though configure works.
### What steps will reproduce the problem?
Compiling on openbsd through cabal

### What version of git-annex are you using? On what operating system?
git-annex-5.20131130 on OpenBSD 5.4

### Please provide any additional information below.

[[!format sh """
The error in question:
[312 of 389] Compiling Assistant.Pairing.Network ( Assistant/Pairing/Network.hs, dist/build/git-annex/git-annex-tmp/Assistant/Pairing/Network.o )

Assistant/Pairing/Network.hs:101:21:
    Not in scope: type constructor or class `IPv4'

Assistant/Pairing/Network.hs:102:21:
    Not in scope: data constructor `IPv4'

Assistant/Pairing/Network.hs:104:21:
    Not in scope: type constructor or class `IPv6'

Assistant/Pairing/Network.hs:105:21:
    Not in scope: data constructor `IPv6'

Assistant/Pairing/Network.hs:108:32:
    Not in scope: data constructor `IPv4'

Assistant/Pairing/Network.hs:109:47:
    Not in scope: data constructor `IPv6'
"""]]

> [[done]]; see comment --[[Joey]]
