[commit: ghc] wip/tc-plugins's head updated: Make TcPlugin part of Plugin so we can eliminate -ftc-plugin (be95bd9)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

Branch 'wip/tc-plugins' now includes:

     1ed1e63 Move withTcPlugins to TcRnDriver, removing need for hs-boot file
     ce850aa Move core2core plugins to a new module Plugins
     be95bd9 Make TcPlugin part of Plugin so we can eliminate -ftc-plugin