[openssl/openssl] ed8af0: Fix a logic flaw in test_mod_exp_zero

[Bernd Edlinger]

  Branch: refs/heads/OpenSSL_1_1_1-stable
  Home:   https://github.com/openssl/openssl
  Commit: ed8af0502167c80ba70522d88e719f874e24ebfd
      https://github.com/openssl/openssl/commit/ed8af0502167c80ba70522d88e719f874e24ebfd
  Author: Bernd Edlinger <bernd.edlinger at hotmail.de>
  Date:   2022-12-21 (Wed, 21 Dec 2022)

  Changed paths:
    M test/exptest.c

  Log Message:
  -----------
  Fix a logic flaw in test_mod_exp_zero

Due to the logic flaw, possible test failures
in this test case might be ignored.

Reviewed-by: Shane Lontis <shane.lontis at oracle.com>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19929)

(cherry picked from commit 42061268ee8f9ae0555d522870740fc91b744f4f)