Code freeze break request

[Matthew Barnes <mbarnes redhat com>]

This Evolution bug came up at the last minute.  Apparently only Gentoo
is crashing from it, but it still might be exploitable.

https://bugzilla.gnome.org/show_bug.cgi?id=612792

Boils down to not passing NULL to a function expecting a NULL-terminated
string list.  The bug has two patches: the first fixes the crash, the
second is some followup work I did to help us catch this sort of thing
in the future (using G_GNUC_NULL_TERMINATED).

Only the first patch is strictly necessary for Evolution 2.30, but both
would be nice.

Matthew Barnes