Allow NSE_TYPE_CONNECT_SSL to be canceled.

This fixes a really bad bug that seems to have been there for a while. Canceling
a nsock connect SSL operation fails with fatal(). I have never seen it in real
life though.

Added a corresponding unit test.

nsock/src/nsock_event.c

@@ -199,6 +199,7 @@ int nsock_event_cancel(nsock_pool ms_pool, nsock_event_id id, int notify) {
   /* First we figure out what list it is in */
   switch (type) {
     case NSE_TYPE_CONNECT:
+    case NSE_TYPE_CONNECT_SSL:
       event_list = &nsp->connect_events;
       break;