Make one-shot a per-registration property

[Kazu Yamamoto (=?iso-2022-jp?B?GyRCOzNLXE9CSScbKEI=?=)]

Hi,

This is just confirmation. Ben's one-shot patch (*1) is included in
master but not included in the ghc-7.10 branch. Is this intentional?
Is it supposed to be merged in GHC 7.12?

(*1) 023439980f6ef6ec051f676279ed2be5f031efe6
     https://phabricator.haskell.org/D347

--Kazu