Force the single-process mode in Evolution and Geary

Force the single-process mode in Evolution and Geary

Bug: https://bugs.webkit.org/show_bug.cgi?id=201033
Origin: https://mail.gnome.org/archives/distributor-list/2019-October/msg00000.html

Since WebKitGTK 2.26 the single-process mode is considered a security
risk and the process limiting APIs have been completely disabled.
This change is transparent for most applications, but Geary and
particularly Evolution (see upstream bug #587) are known to have
problems in multi-process mode. This has already been fixed in Geary
3.33.91 and in Evolution 3.34.1.

Although the API to set the single-process model is no longer
available, it is still possible to do it internally. This patch does
that for Evolution and Geary.

This is a temporary workaround and it is especially meant for stable
distributions and security updates, where patching or updating the
affected apps is not an option.
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Gbp-Pq: Name force-single-process.patch