Win32: unimplement thread result

This is never used currently. Removing it simplifies the next commits.

include/vlc_threads.h

@@ -129,7 +129,6 @@ struct vlc_timer_t
 typedef struct
 {
     HANDLE handle;
-    void  *result;
 #if defined( UNDER_CE )
     HANDLE cancel_event;
 #endif

src/misc/w32thread.c

@@ -427,7 +427,7 @@ static unsigned __stdcall vlc_entry (void *p)
 #endif
 
     vlc_threadvar_set (cancel_key, &cancel_data);
-    data.handle->result = data.func (data.data);
+    data.func (data.data);
     return 0;
 }
 
@@ -505,8 +505,7 @@ void vlc_join (vlc_thread_t handle, void **result)
                                                         == WAIT_IO_COMPLETION);
 
     CloseHandle (handle->handle);
-    if (result)
-        *result = handle->result;
+    assert (result == NULL); /* <- FIXME if ever needed */
 #ifdef UNDER_CE
     CloseHandle (handle->cancel_event);
 #endif