KolabMailSideCache: added dummy to private struct
KolabMailSideCache: added dummy to private struct

* added a dummy member to KolabMailSideCachePrivate
  so the object can be instantiated
  (fixes a 'sizeof(KolabMailSideCachePrivate) != 0'
  assertion failure)

GNOME/evolution-kolab,GNOME/evolution-kolab