[openssl/openssl] adc6b4: Fix regression of no-posix-io builds

[Tomáš Mráz]

  Branch: refs/heads/openssl-3.1
  Home:   https://github.com/openssl/openssl
  Commit: adc6b42612511bab57ed85f5fae4d1a4e026dd06
      https://github.com/openssl/openssl/commit/adc6b42612511bab57ed85f5fae4d1a4e026dd06
  Author: Tomas Mraz <tomas at openssl.org>
  Date:   2023-04-25 (Tue, 25 Apr 2023)

  Changed paths:
    M ssl/ssl_cert.c

  Log Message:
  -----------
  Fix regression of no-posix-io builds

Instead of using stat() to check if a file is a directory
we just skip . and .. as a workaround.

Reviewed-by: Hugo Landau <hlandau at openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit at gmail.com>
(Merged from https://github.com/openssl/openssl/pull/20786)

(cherry picked from commit 3155b5a90e6ad9c7369d09e70e81686f4b321a73)