zlib: fix build for windows platforms
zlib: fix build for windows platforms

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