do not build or install any piece of BZ when --without-bugzilla

Signed-off-by: Michal Toman <mtoman@redhat.com>
Signed-off-by: Jiri Moskovcak <jmoskovc@redhat.com>
do not build or install BZ dependencies when --without-bugzilla

Signed-off-by: Michal Toman <mtoman@redhat.com>
Signed-off-by: Jiri Moskovcak <jmoskovc@redhat.com>
tweak SPEC for openSUSE abrt/abrt#589

Signed-off-by: Jiri Moskovcak <jmoskovc@redhat.com>