Cleanse ECX private key stack buffers

Author: JeremiahM37

src/wp_ecx_kmgmt.c

@@ -698,6 +698,9 @@ static int wp_ecx_match_priv_key(const wp_Ecx* ecx1, const wp_Ecx* ecx2)
         ok = 0;
     }
 
+    OPENSSL_cleanse(key1, sizeof(key1));
+    OPENSSL_cleanse(key2, sizeof(key2));
+
     WOLFPROV_LEAVE(WP_LOG_COMP_KE, __FILE__ ":" WOLFPROV_STRINGIZE(__LINE__), ok);
     return ok;
 }