deprecate the original (numeric-only) scheme, and replace with the
CRYPTO_THREADID object. This hides the platform-specifics and should reduce
the possibility for programming errors (where failing to explicitly check
both thread ID forms could create subtle, platform-specific bugs).

Thanks to Bodo, for invaluable review and feedback.

from the OpenSSL distribution.

CRYPTO_get_idptr_callback(), CRYPTO_thread_idptr() for a 'void *' type
thread ID, since the 'unsigned long' type of the existing thread ID
does not always work well.

defering freeing in OBJ_cleanup().

CRYPTO_malloc_init in FAQ.

(This were in 0.9.7-stable and 0.9.8-stable, but not in HEAD so far.)

integer type.

Well, no-options seem to be busted in HEAD currently, which should/will be
fixed one way or another (see PR#989 for a possible alternative).