[openssl/openssl] 0f644b: replace strstr() with strchr() for single characters

[rilysh]

  Branch: refs/heads/master
  Home:   https://github.com/openssl/openssl
  Commit: 0f644b96d209443b4566f7e86e3be2568292e75b
      https://github.com/openssl/openssl/commit/0f644b96d209443b4566f7e86e3be2568292e75b
  Author: rilysh <nightquick at proton.me>
  Date:   2024-01-25 (Thu, 25 Jan 2024)

  Changed paths:
    M apps/engine.c
    M crypto/dso/dso_dl.c
    M crypto/dso/dso_dlfcn.c
    M ssl/ssl_conf.c

  Log Message:
  -----------
  replace strstr() with strchr() for single characters

strstr() is used to match multiple characters in the haystack,
whereas strchr() is used to matched only single character.

CLA: trivial

Reviewed-by: Tom Cosgrove <tom.cosgrove at arm.com>
Reviewed-by: Matt Caswell <matt at openssl.org>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/23347)