Returns true if the type is a socket

Property definitions

core $ NativeFileStat :: is_sock
	# Returns true if the type is a socket
	fun is_sock: Bool `{
#ifdef _WIN32
	return 0;
#else
	return S_ISSOCK(self->st_mode);
#endif
	`}
lib/core/file.nit:1504,2--1511,3