test: update test20/1322 for eglibc bug workaround

The tests 20 and 1322 are using getaddrinfo of libc for resolving. In
eglibc-2.19 there is a memory leakage and invalid free bug which
surfaces in some special circumstances (PF_UNSPEC hint with invalid or
non-existent names). The valgrind runs in testing fail in these
situations.

As the tests 20/1322 are not specific on either protocol (IPv4/IPv6)
this commit changes the hints to IPv4 protocol by passing `--ipv4` flag
on the tests' command line.  This prevents the valgrind failures.