[openssl/openssl] ef7a9b: Make OSSL_LIB_CTX_load_config thread safe

[Hugo Landau]

  Branch: refs/heads/master
  Home:   https://github.openssl.org/openssl/openssl
  Commit: ef7a9b44f04ef18b652cb47cd9eb3826301cca9e
      https://github.openssl.org/openssl/openssl/commit/ef7a9b44f04ef18b652cb47cd9eb3826301cca9e
  Author: Hugo Landau <hlandau at openssl.org>
  Date:   2022-06-01 (Wed, 01 Jun 2022)

  Changed paths:
    M crypto/conf/conf_mod.c
    M test/threadstest.c

  Log Message:
  -----------
  Make OSSL_LIB_CTX_load_config thread safe

Fixes #18226.

Reviewed-by: Matt Caswell <matt at openssl.org>
Reviewed-by: Paul Dale <pauli at openssl.org>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18331)