wininet(1/3): Only initialize SSL_CTX once

[Juan Lang]

Hi Hans,

> The bug reporter sees long delays between torrents starting up after
> applying these patches, which makes we wonder if the ssl lock effectively
> serializes secure https requests?

There isn't a single SSL lock.  There's an interlocked exchange for
assigning SSL_CTX, which should only be created once except in a race
between threads.  There's a critical section to protect against two
threads initializing the SSL library at the same time.  Finally, there
are a number of SSL locks (CRYPTO_num_locks() many, specifically) that
OpenSSL uses.  When I was debugging it, there are at least 16 of them.
 So I don't think serialization of locks is the root cause of the
slowdown.

> Would patch 1 and 3 not be sufficient to fix the utorrent crash?

I don't think so.  Other apps have had similar crashes with the
equivalent of patch 2 not applied, and the OpenSSL man page warns of
random crashes due to failing to implement and set these callbacks.
--Juan