CONF_modules_unload should fail if CONF_modules_finish fails

CONF_modules_unload should fail if CONF_modules_finish fails

The module_list_lock is used by CONF_modules_unload(). That function relies
on the RUN_ONCE in CONF_modules_finish() to initialise that lock. However
if the RUN_ONCE fails that failure is not propagated to
CONF_modules_unload() and so it erroneously tries to use the lock anyway.

Found due to:
https://github.com/openssl/openssl/pull/18355#issuecomment-1144734604

Reviewed-by: Todd Short <todd.short@me.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18460)