MEDIUM: ssl: remote the proxy argument from most functions

MEDIUM: ssl: remote the proxy argument from most functions

Most of the SSL functions used to have a proxy argument which was mostly
used to be able to emit clean errors using Alert(). First, many of them
were converted to memprintf() and don't require this pointer anymore.
Second, the rare which still need it also have either a bind_conf argument
or a server argument, both of which carry a pointer to the relevant proxy.

So let's now get rid of it, it needlessly complicates the API and certain
functions already have many arguments.