schannel: Disable ALPN for Wine since it is causing problems

- Disable ALPN on Wine.

- Don't pass input secbuffer when ALPN is disabled.

When ALPN support was added a change was made to pass an input secbuffer
to initialize the context. When ALPN is enabled the buffer contains the
ALPN information, and when it's disabled the buffer is empty. In either
case this input buffer caused problems with Wine and connections would
not complete.

Bug: https://github.com/curl/curl/issues/983
Reported-by: Christian Fillion