Fix potential double free through SRP_user_pwd_set1_ids()

Fix potential double free through SRP_user_pwd_set1_ids()

If SRP_user_pwd_set1_ids() fails during one of the duplications, or id
is NULL, then the old pointer values are still stored but they are now dangling.
Later when SRP_user_pwd_free() is called these are freed again,
leading to a double free.

Although there are no such uses in OpenSSL as far as I found,
it's still a public API.

CLA: trivial

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/25655)

(cherry picked from commit 792b2c8da283d4230caa761ea6f5d050cb5795e7)