If SSL was unavailable but requested (should never happen)
MiniHttpServer::incomingConnection() would have crashed on
dereferencing unset member client. Rework the run-time conditioning
on SSL to sit entirely inside the #if-ery on SSL support, so that
client is at least set in each code-path.
Change-Id: I9a8ee8e4186e16dd0d00b7f9cc9b988f0b4c62ff
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@theqtcompany.com>