Changes to ghc

Changes to ghc:
commit e734c18969de4e41aef6671822c164ee039291d7
Author: Joachim Breitner <mail@joachim-breitner.de>
Date:   Wed Oct 23 11:24:24 2013 +0200

    Change type of `errMsgSpans` field of `ErrMsg` to `SrcSpan`

    It was `[SrcSpan]`, but never ever contained more than one span.