Fixed issue #149.

scripts/toolchain.lua

@@ -179,7 +179,7 @@ function toolchain(_buildDir, _libDir)
 		tvosPlatform = _OPTIONS["with-tvos"]
 	end
 
-	local windowsPlatform = os.getenv("WindowsSDKVersion") or "8.1"
+	local windowsPlatform = string.gsub(os.getenv("WindowsSDKVersion") or "8.1", "\\", "")
 	if _OPTIONS["with-windows"] then
 		windowsPlatform = _OPTIONS["with-windows"]
 	end