Allow building with deprecated GTK+ symbols
    
    Commit 76b6ce8 added a downstream patch to remove the use of the
    deprecated stock items. This however added new strings that the current
    avahi tarball doesn't ship translations for, and as such we shouldn't do
    it downstream.
    
    Instead, just allow the deprecated GTK+ symbols. The deprecated API and
    -Werror should never have been enabled in the tarball builds in the
    first place.
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1001676