winnt.h should not be self-contained, it must depend on windef.h so
that STRICT works correctly; moved some definitions back to windef.h
where they belong, and removed a couple of definitions that don't
exist on Windows.

diff --git a/server/mutex.c b/server/mutex.c
index f38fd8d..fe76553 100644
--- a/server/mutex.c
+++ b/server/mutex.c
@@ -25,7 +25,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-#include "winnt.h"
+#include "windef.h"
 
 #include "handle.h"
 #include "thread.h"