(VALGRIND_FD): New constant, set to 21. Added a comment that refers
to PROTECTED_FDS in unix.exp. (site.exp): Set lyskomd_host to whatever 127.0.0.1 resolves to, or 127.0.0.1 if it cannot be looked up at all. Set valgrind_fd to the constant defined in VALGRIND_FD. (valgrind.wrap): Use VALGRIND_FD, instead of hardcoding the value in two places. Changed the valgrind file descriptor to 21, which is currently the highest reserved file descriptor.