Fixed the condition for waking up/creating another thread.
If there is some work to do (if the request queue is not empty),
a thread should be woken or created.
The condition was incorrect since 18c9b345b4
- get rid of casts between int and HANDLE.
- store file descriptor in TP_connection_generic to get
rid of multiple mysql_socket_getfd(c->thd->net.vio->mysql_socket))
Also support named pipes (no reason not to support, since it is easy)
- Fix win64 pointer truncation warnings
(usually coming from misusing 0x%lx and long cast in DBUG)
- Also fix printf-format warnings
Make the above mentioned warnings fatal.
- fix pthread_join on Windows to set return value.
