Survive fedora's openssl in our benchmarks

Apparently fedora currently has ECDH but not P224. This isn't a huge
deal, since we no longer use OpenSSL's P224 ever (see #9780 and
72c1e5acfe1c6). But we shouldn't have segfaulting benchmarks really.

Fixes bug 10835; bugfix on 0.2.4.8-alpha.