wininet(1/3): Only initialize SSL_CTX once

[Hans Leidekker]

Hi Juan,

> These patches collectively fix bug 18364, which was a crash in OpenSSL
> in a multithreaded app (utorrent.exe.)

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?

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

 -Hans