fix a typo in comments: normaliseFfiType

Summary:
The function is defined in TcForeign module, but misspelled comment
makes it hard to find

Reviewers: austin

Reviewed By: austin

Subscribers: thomie, carter, ezyang, simonmar

Differential Revision: https://phabricator.haskell.org/D368
Pass in CXX to libffi's configure script.

Reviewers: austin

Reviewed By: austin

Subscribers: thomie, carter, ezyang, simonmar

Differential Revision: https://phabricator.haskell.org/D370

GHC Trac Issues: #9720