Testsuite: Add PORT_DYNAMIC (Bug 1775) This avoids problems on OpenBSD with SO_REUSEADDR. On OpenBSD SO_REUSEADDR only works if the IP address AND the EUID of the bind(2) calls match. In 0562 Exim binds to 1225 as euid=0, in 0564 runtest tries to bind to 01225 as the user running the tests. Thanks to Kirill Miazine for working this out.