[openssl/openssl] d8e2dc: Add sensitive memory clean in priv encode

[pauli]

  Branch: refs/heads/openssl-3.0
  Home:   https://github.openssl.org/openssl/openssl
  Commit: d8e2dc576571de48f85d106d1f3e5da604bd2c9a
      https://github.openssl.org/openssl/openssl/commit/d8e2dc576571de48f85d106d1f3e5da604bd2c9a
  Author: Kan <chenxinpingc2306 at 163.com>
  Date:   2022-06-16 (Thu, 16 Jun 2022)

  Changed paths:
    M crypto/dh/dh_ameth.c
    M crypto/dsa/dsa_ameth.c
    M crypto/ec/ec_ameth.c
    M crypto/rsa/rsa_ameth.c

  Log Message:
  -----------
  Add sensitive memory clean in priv encode

Fixes #18540

Reviewed-by: Tomas Mraz <tomas at openssl.org>
Reviewed-by: Paul Dale <pauli at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18541)

(cherry picked from commit 16249341bb64329c2542c3d1e23b97ed3c44fad3)