[evolution-data-server] Hard code freeze break approval plea

[Milan Crha <mcrha redhat com>]

        Hello,
as is described in bug:
https://bugzilla.gnome.org/show_bug.cgi?id=755075

a recent change in GLib 2.45.8
https://git.gnome.org/browse/glib/commit/?id=00933dfc9cc525963c6833d3

broke evolution-data-server settings save/load for mail accounts.

The reason is that the evolution-data-server uses a hack to copy
GParamSpec structure, while the GLib change uses private structure
member, which was not properly copied, thus the code failed to notice
the changes in GObject properties.

There is a fix available for the evolution-data-server, attached in the
above bug report, which fixes the evolution-data-server side.

I'd like to ask for an approval to commit it before the 3.18.0, because
the bug report is a blocker for the evolution-data-server release.
Either that, or revert the change in GLib, but fixing the evolution-
data-server feels more correct.
        Thanks and bye,
        Milan