Automate GCC driver wrapper
Everytime we upgrade the GCC version this wrapper needed updating.
This is a big fragile and we kept forgetting it.
Instead automate it so we don't have to worry about it.
Test Plan: ./validate
Reviewers: austin, bgamari
Reviewed By: bgamari
Subscribers: thomie, #ghc_windows_task_force
Differential Revision: https://phabricator.haskell.org/D2820
GHC Trac Issues: Trac #12871