Git: compile fix

bool operator<(const CommitData::StateFilePair &a, ...) needs to
be defined _after_ Q_DECLARE_OPERATORS_FOR_FLAGS(Git::Internal::FileStates)

Change-Id: I03d5d79e2b77d0063c588aff1c549afd78a0ee3d
Reviewed-by: hjk <qthjk@ovi.com>