[PlatformDetection] remove pointless IsPosix field
[PlatformDetection] remove pointless IsPosix field

Dynalon/banshee-osx,stsundermann/banshee,Carbenium/banshee,babycaseny/banshee,stsundermann/banshee,dufoli/banshee,lamalex/Banshee,mono-soc-2011/banshee,arfbtwn/banshee,Dynalon/banshee-osx,petejohanson/banshee,ixfalia/banshee,babycaseny/banshee,dufoli/banshee,lamalex/Banshee,babycaseny/banshee,lamalex/Banshee,GNOME/banshee,dufoli/banshee,ixfalia/banshee,ixfalia/banshee,arfbtwn/banshee,babycaseny/banshee,babycaseny/banshee,allquixotic/banshee-gst-sharp-work,mono-soc-2011/banshee,petejohanson/banshee,babycaseny/banshee,allquixotic/banshee-gst-sharp-work,GNOME/banshee,ixfalia/banshee,mono-soc-2011/banshee,ixfalia/banshee,GNOME/banshee,Carbenium/banshee,arfbtwn/banshee,GNOME/banshee,Carbenium/banshee,allquixotic/banshee-gst-sharp-work,stsundermann/banshee,arfbtwn/banshee,directhex/banshee-hacks,arfbtwn/banshee,mono-soc-2011/banshee,Dynalon/banshee-osx,GNOME/banshee,petejohanson/banshee,arfbtwn/banshee,GNOME/banshee,directhex/banshee-hacks,arfbtwn/banshee,dufoli/banshee,ixfalia/banshee,directhex/banshee-hacks,ixfalia/banshee,allquixotic/banshee-gst-sharp-work,petejohanson/banshee,stsundermann/banshee,Carbenium/banshee,babycaseny/banshee,Dynalon/banshee-osx,dufoli/banshee,babycaseny/banshee,GNOME/banshee,lamalex/Banshee,Dynalon/banshee-osx,stsundermann/banshee,lamalex/Banshee,ixfalia/banshee,lamalex/Banshee,stsundermann/banshee,mono-soc-2011/banshee,petejohanson/banshee,mono-soc-2011/banshee,mono-soc-2011/banshee,dufoli/banshee,allquixotic/banshee-gst-sharp-work,directhex/banshee-hacks,dufoli/banshee,arfbtwn/banshee,directhex/banshee-hacks,dufoli/banshee,directhex/banshee-hacks,allquixotic/banshee-gst-sharp-work,Carbenium/banshee,petejohanson/banshee,Dynalon/banshee-osx,Dynalon/banshee-osx,Carbenium/banshee,stsundermann/banshee,GNOME/banshee,Dynalon/banshee-osx,stsundermann/banshee