3proxy --help (and the usage message of a bad invocation) now lists
what the build was made with: TLS and its backend, RADIUS, PCRE, IPv6,
UNIX sockets, the built-in HTTP server, transparency, ODBC and the
optional proxy services. The test runner reads the list before the
first case and the cases state the features they need with
t.skip_unless(), so a build without a feature skips its cases instead
of failing them; a binary too old to report anything skips the cases
with needs and runs the rest.
