Switch from memset_s() -> explicit_bzero().

memset_s() (and all of Annex K) is likely to be removed from the
a future version of the standard.

plugins/sudoers/auth/sia.c

@@ -90,7 +90,7 @@ sudo_sia_verify(struct passwd *pw, char *prompt, sudo_auth *auth,
 
     /* Check password and zero out plaintext copy. */
     rc = sia_ses_authent(NULL, pass, siah);
-    memset_s(pass, SUDO_CONV_REPL_MAX, 0, strlen(pass));
+    explicit_bzero(pass, strlen(pass));
     free(pass);
 
     if (rc == SIASUCCESS)