cosmetics
QA - prune some warnings

Distromap.hs -> pvu_map is provided by upstream arguments, no need to provide it once more
Merge.hs -> warning prune: xs variable name is already in use
Portage/GHCCore.hs -> warning prune: pi var name in use
Portage/Host.hs -> prune declared but unused variables to _
Merge pull request #15 from Heather/master

cosmetics