Fix a name mismatch between host_prefix and tools_prefix
Fix a name mismatch between host_prefix and tools_prefix

I am not sure it is what was meant to be done, but it is the only
thing that makes sense as host_prefix does not exist anywhere.

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