Make default values by ERR_get_error_all() and friends more consistent

Unset data defaults to the empty string ("") or 0.

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9948)
2 files changed