Fix potential double free in rsa_keygen pairwise test.
Fix potential double free in rsa_keygen pairwise test.

It should never hit this branch of code, so there is no feasible test.
Found due to a similar issue in PR #12176.

Reviewed-by: Matt Caswell <1fa2ef4755a9226cb9a0a4840bd89b158ac71391@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/12177)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl