UNC paths are absolute paths as well (#6061)

std/haxe/io/Path.hx

@@ -301,6 +301,7 @@ class Path {
 	public static function isAbsolute ( path : String ) : Bool {
 		if (StringTools.startsWith(path, '/')) return true;
 		if (path.charAt(1) == ':') return true;
+		if (StringTools.startsWith(path, '\\\\')) return true;
 		return false;
 	}