gst-ffmpeg: only write options on windows
gst-ffmpeg: only write options on windows

BigBrother-International/gst-cerbero,lubosz/cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,centricular/cerbero,EricssonResearch/cerbero,shoreflyer/cerbero,multipath-rtp/cerbero,centricular/cerbero,nirbheek/cerbero,nicolewu/cerbero,nirbheek/cerbero-old,shoreflyer/cerbero,BigBrother-International/gst-cerbero,ford-prefect/cerbero,atsushieno/cerbero,lubosz/cerbero,freedesktop-unofficial-mirror/gstreamer__cerbero,sdroege/cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,ylatuya/cerbero,davibe/cerbero,GStreamer/cerbero,jackjansen/cerbero-2013,fluendo/cerbero,OptoFidelity/cerbero,davibe/cerbero,BigBrother-International/gst-cerbero,jackjansen/cerbero,atsushieno/cerbero,nzjrs/cerbero,freedesktop-unofficial-mirror/gstreamer__sdk__cerbero,ylatuya/cerbero,ramaxlo/cerbero,davibe/cerbero,freedesktop-unofficial-mirror/gstreamer__cerbero,flexVDI/cerbero,sdroege/cerbero,centricular/cerbero,jackjansen/cerbero,flexVDI/cerbero,jackjansen/cerbero-2013,multipath-rtp/cerbero,nirbheek/cerbero,justinjoy/cerbero,ikonst/cerbero,nirbheek/cerbero,jackjansen/cerbero,BigBrother-International/gst-cerbero,EricssonResearch/cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,brion/cerbero,ramaxlo/cerbero,centricular/cerbero,superdump/cerbero,sdroege/cerbero,ikonst/cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,sdroege/cerbero,freedesktop-unofficial-mirror/gstreamer__sdk__cerbero,cee1/cerbero-mac,brion/cerbero,jackjansen/cerbero-2013,cee1/cerbero-mac,ylatuya/cerbero,ramaxlo/cerbero,nirbheek/cerbero-old,nzjrs/cerbero,ylatuya/cerbero,nicolewu/cerbero,EricssonResearch/cerbero,flexVDI/cerbero,fluendo/cerbero,superdump/cerbero,ramaxlo/cerbero,OptoFidelity/cerbero,fluendo/cerbero,jackjansen/cerbero,BigBrother-International/gst-cerbero,justinjoy/cerbero,centricular/cerbero,brion/cerbero,jackjansen/cerbero-2013,AlertMe/cerbero,sdroege/cerbero,lubosz/cerbero,ford-prefect/cerbero,atsushieno/cerbero,justinjoy/cerbero,shoreflyer/cerbero,GStreamer/cerbero,freedesktop-unofficial-mirror/gstreamer__cerbero,fluendo/cerbero,flexVDI/cerbero,jackjansen/cerbero-2013,ford-prefect/cerbero,GStreamer/cerbero,AlertMe/cerbero,multipath-rtp/cerbero,shoreflyer/cerbero,cee1/cerbero-mac,nzjrs/cerbero,nzjrs/cerbero,atsushieno/cerbero,multipath-rtp/cerbero,nirbheek/cerbero-old,GStreamer/cerbero,nzjrs/cerbero,flexVDI/cerbero,superdump/cerbero,nirbheek/cerbero-old,GStreamer/cerbero,ikonst/cerbero,EricssonResearch/cerbero,brion/cerbero,OptoFidelity/cerbero,cee1/cerbero-mac,lubosz/cerbero,AlertMe/cerbero,brion/cerbero,nirbheek/cerbero,justinjoy/cerbero,freedesktop-unofficial-mirror/gstreamer__cerbero,AlertMe/cerbero,multipath-rtp/cerbero,nicolewu/cerbero,davibe/cerbero,freedesktop-unofficial-mirror/gstreamer__sdk__cerbero,superdump/cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,ramaxlo/cerbero,OptoFidelity/cerbero,EricssonResearch/cerbero,ikonst/cerbero,ikonst/cerbero,freedesktop-unofficial-mirror/gstreamer__sdk__cerbero,atsushieno/cerbero,AlertMe/cerbero,ford-prefect/cerbero,shoreflyer/cerbero,fluendo/cerbero