Backport tinc 1.1's str2net() function. The old function could get confused by short-hand IPv6 notation (using ::) and mistake them for MAC addresses. The new code is more strict; it will correctly handle all short-hand addresses, and will return an error when an address has trailing garbage instead of ignoring it.
Remove the call to RAND_load_file(). It might have been necessary for some very old version of OpenSSL, but the currently minimum required version for tinc will do a proper initialization of its PRNG automatically. LibreSSL of course does the right thing too, and its RAND_load_file() is just a dummy.