Fix compile failure with no-threads
Fix compile failure with no-threads

The async code was causing a compile failure if no-threads was used.

Reviewed-by: Kurt Roeckx <bb87b47479d83cec3c76132206933257ded727b2@openssl.org>

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl