bootstrap: add 'mingw-w64-tools' if target platform is Windows
bootstrap: add 'mingw-w64-tools' if target platform is Windows

https://bugzilla.gnome.org/show_bug.cgi?id=750228

jackjansen/cerbero,shoreflyer/cerbero,GStreamer/cerbero,multipath-rtp/cerbero,fluendo/cerbero,atsushieno/cerbero,sdroege/cerbero,justinjoy/cerbero,OptoFidelity/cerbero,multipath-rtp/cerbero,EricssonResearch/cerbero,shoreflyer/cerbero,GStreamer/cerbero,justinjoy/cerbero,flexVDI/cerbero,sdroege/cerbero,sdroege/cerbero,sdroege/cerbero,EricssonResearch/cerbero,EricssonResearch/cerbero,nirbheek/cerbero,flexVDI/cerbero,multipath-rtp/cerbero,OptoFidelity/cerbero,atsushieno/cerbero,fluendo/cerbero,nirbheek/cerbero,nirbheek/cerbero,justinjoy/cerbero,centricular/cerbero,atsushieno/cerbero,flexVDI/cerbero,EricssonResearch/cerbero,sdroege/cerbero,fluendo/cerbero,shoreflyer/cerbero,centricular/cerbero,justinjoy/cerbero,multipath-rtp/cerbero,jackjansen/cerbero,multipath-rtp/cerbero,atsushieno/cerbero,shoreflyer/cerbero,OptoFidelity/cerbero,flexVDI/cerbero,centricular/cerbero,jackjansen/cerbero,flexVDI/cerbero,OptoFidelity/cerbero,jackjansen/cerbero,GStreamer/cerbero,nirbheek/cerbero,atsushieno/cerbero,GStreamer/cerbero,fluendo/cerbero,shoreflyer/cerbero,centricular/cerbero,GStreamer/cerbero,fluendo/cerbero,EricssonResearch/cerbero,centricular/cerbero