dumpon: update OpenSSL initialization call

ERR_load_crypto_strings() was deprecated in OpenSSL 1.1.0, and explicit
initialization is generally not reqiured. In the case of dumpon however
we initialize prior to entering capability mode, so replace with an
OPENSSL_init_crypto call.

Reviewed by: def, Pierre Pronchery
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D40353