update FAQ

Multi-threaded applications must provide two callback functions to

OpenSSL by calling CRYPTO_set_locking_callback() and

CRYPTO_set_id_callback(), for all versions of OpenSSL up to and

including 0.9.8[abc...]. As of version 0.9.9, CRYPTO_set_id_callback()

including 0.9.8[abc...]. As of version 1.0.0, CRYPTO_set_id_callback()

and associated APIs are deprecated by CRYPTO_THREADID_set_callback()

and friends. This is described in the threads(3) manpage.