[Bug c++/69864] Fix various Wnarrowing minor issues

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69864

--- Comment #12 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #11)
> Patch: https://gcc.gnu.org/ml/gcc-patches/2016-02/msg01326.html

Committed to trunk.