libffi: do not harcode version in libffi libdir
libffi: do not harcode version in libffi libdir

flexVDI/cerbero,superdump/cerbero,ramaxlo/cerbero,multipath-rtp/cerbero,GStreamer/cerbero,OptoFidelity/cerbero,centricular/cerbero,davibe/cerbero,ford-prefect/cerbero,nirbheek/cerbero,brion/cerbero,flexVDI/cerbero,freedesktop-unofficial-mirror/gstreamer__cerbero,shoreflyer/cerbero,freedesktop-unofficial-mirror/gstreamer__sdk__cerbero,GStreamer/cerbero,EricssonResearch/cerbero,ikonst/cerbero,centricular/cerbero,centricular/cerbero,fluendo/cerbero,jackjansen/cerbero,nzjrs/cerbero,OptoFidelity/cerbero,OptoFidelity/cerbero,nzjrs/cerbero,atsushieno/cerbero,ikonst/cerbero,freedesktop-unofficial-mirror/gstreamer__cerbero,fluendo/cerbero,centricular/cerbero,GStreamer/cerbero,shoreflyer/cerbero,nirbheek/cerbero,shoreflyer/cerbero,nzjrs/cerbero,AlertMe/cerbero,AlertMe/cerbero,sdroege/cerbero,ford-prefect/cerbero,lubosz/cerbero,AlertMe/cerbero,atsushieno/cerbero,atsushieno/cerbero,justinjoy/cerbero,fluendo/cerbero,lubosz/cerbero,flexVDI/cerbero,superdump/cerbero,fluendo/cerbero,freedesktop-unofficial-mirror/gstreamer__cerbero,lubosz/cerbero,atsushieno/cerbero,sdroege/cerbero,multipath-rtp/cerbero,GStreamer/cerbero,nirbheek/cerbero-old,multipath-rtp/cerbero,ford-prefect/cerbero,brion/cerbero,superdump/cerbero,jackjansen/cerbero,superdump/cerbero,justinjoy/cerbero,EricssonResearch/cerbero,ikonst/cerbero,ramaxlo/cerbero,OptoFidelity/cerbero,lubosz/cerbero,centricular/cerbero,shoreflyer/cerbero,justinjoy/cerbero,sdroege/cerbero,brion/cerbero,brion/cerbero,ramaxlo/cerbero,ramaxlo/cerbero,sdroege/cerbero,GStreamer/cerbero,brion/cerbero,fluendo/cerbero,nzjrs/cerbero,justinjoy/cerbero,AlertMe/cerbero,freedesktop-unofficial-mirror/gstreamer__sdk__cerbero,multipath-rtp/cerbero,EricssonResearch/cerbero,sdroege/cerbero,nirbheek/cerbero,EricssonResearch/cerbero,nirbheek/cerbero-old,nirbheek/cerbero-old,ikonst/cerbero,flexVDI/cerbero,jackjansen/cerbero,jackjansen/cerbero,freedesktop-unofficial-mirror/gstreamer__sdk__cerbero,shoreflyer/cerbero,freedesktop-unofficial-mirror/gstreamer__cerbero,ramaxlo/cerbero,multipath-rtp/cerbero,davibe/cerbero,flexVDI/cerbero,AlertMe/cerbero,ford-prefect/cerbero,ikonst/cerbero,nirbheek/cerbero-old,nzjrs/cerbero,davibe/cerbero,freedesktop-unofficial-mirror/gstreamer__sdk__cerbero,EricssonResearch/cerbero,davibe/cerbero,atsushieno/cerbero,nirbheek/cerbero