PostTcType replaced with TypeAnnot

Summary: Compiles and passes validate. Transition in renamer

Test Plan: sh validate

Reviewers: austin

Subscribers: simonmar, relrod, ezyang, carter

Differential Revision: https://phabricator.haskell.org/D157
Fix lint warnings
Merge branch 'wip/landmine-param-family' of github.com:alanz/ghc into wip/landmine-param-family