fix warning about missing NAME keyword arg at start-thread

This gets rid of a warning like

```
;Compiler warnings for "home:hunchentoot-patch;hunchentoot;taskmaster.lisp.newest" :
;   In (HUNCHENTOOT:CREATE-REQUEST-HANDLER-THREAD (HUNCHENTOOT:ONE-THREAD-PER-CONNECTION-TASKMASTER T)) inside an anonymous lambda form: In the call to HUNCHENTOOT:START-THREAD with arguments (HUNCHENTOOT:TASKMASTER #'(LAMBDA NIL (HUNCHENTOOT::HANDLE-INCOMING-CONNECTION% HUNCHENTOOT:TASKMASTER HUNCHENTOOT::SOCKET)) :NAME (FORMAT NIL (HUNCHENTOOT::TASKMASTER-WORKER-THREAD-NAME-FORMAT HUNCHENTOOT:TASKMASTER) (HUNCHENTOOT:CLIENT-AS-STRING HUNCHENTOOT::SOCKET))),
;     the keyword argument :NAME is not recognized by the definition of HUNCHENTOOT:START-THREAD visible in the current compilation unit.
;   In (HUNCHENTOOT:EXECUTE-ACCEPTOR (HUNCHENTOOT:MULTI-THREADED-TASKMASTER)) inside an anonymous lambda form: In the call to HUNCHENTOOT:START-THREAD with arguments (HUNCHENTOOT:TASKMASTER #'(LAMBDA NIL (HUNCHENTOOT:ACCEPT-CONNECTIONS (HUNCHENTOOT:TASKMASTER-ACCEPTOR HUNCHENTOOT:TASKMASTER))) :NAME (FORMAT NIL "hunchentoot-listener-~A:~A" (OR (HUNCHENTOOT:ACCEPTOR-ADDRESS (HUNCHENTOOT:TASKMASTER-ACCEPTOR HUNCHENTOOT:TASKMASTER)) "*") (HUNCHENTOOT:ACCEPTOR-PORT (HUNCHENTOOT:TASKMASTER-ACCEPTOR HUNCHENTOOT:TASKMASTER)))),
;     the keyword argument :NAME is not recognized by the definition of HUNCHENTOOT:START-THREAD visible in the current compilation unit.
```