15.10: Evolution 3.16 won't use proportional fonts

[Paul Smith]

Hi all; I found this bug in Evolution 3.16.5 in Ubuntu GNOME:

https://bugs.launchpad.net/ubuntu/+source/evolution/+bug/1518988

There's a link there to a simple two-line change which fixes the issue
and was applied to Evo 3.18, but it would be great if someone could get
this fix backported to the Evolution 3.16 version in Ubuntu 15.10.

Cheers!