Plugins: Add libgeary-client to rpath
Since we moved libgeary-client to a subdirectory, running ldd over the plug-ins shows they cannot find the library. They will still likely work in Geary, inheriting the library but we should still fix it in order not to trip up packagers' linters.
$ for f in result/lib/**/lib*.so result/bin/.*-wrapped
if ldd $f | grep 'not found'
echo $f
end
end
libgeary-client-3.37.so => not found
result/lib/geary/plugins/desktop-notifications/libdesktop-notifications.so
libgeary-client-3.37.so => not found
result/lib/geary/plugins/email-templates/libemail-templates.so
libgeary-client-3.37.so => not found
result/lib/geary/plugins/folder-highlight/libfolder-highlight.so
libgeary-client-3.37.so => not found
result/lib/geary/plugins/notification-badge/libnotification-badge.so
libgeary-client-3.37.so => not found
result/lib/geary/plugins/sent-sound/libsent-sound.so
libgeary-client-3.37.so => not found
result/lib/geary/plugins/special-folders/libspecial-folders.so