Use right order of sr_rpm_package_free in sr_rpm_package_uniq

Fixes a crash reported in rhbz#1010948 and even fixes the failing
tests on https://build.opensuse.org

Signed-off-by: Jakub Filak <jfilak@redhat.com>
Merge pull request #107 from abrt/rhbz1010948

Use right order of sr_rpm_package_free in sr_rpm_package_uniq