Avoid test_errstr in a cross compiled configuration

There's too high a chance that the openssl app and perl get different
messages for some error numbers.

[extended tests]

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7699)

(cherry picked from commit 0777de15ff09105593c7e778cf47f97a9144d273)