ECDH p224 benchmarks segfault on Fedora
Due to Fedora's particularly weird OpenSSL, running ./test/bench gives me:
...
##### ecdh_p256
Complete ECDH P-256 handshakes (2 public and 2 private ops):
6.155905 millisec each.
##### ecdh_p224
Segmentation fault (core dumped)
This isn't a huge deal, since we no longer use OpenSSL's P224 ever (see #9780 (moved) and 72c1e5acfe1c6). But we shouldn't have segfaulting benchmarks really.