guiddef.h: Remove GUID_NULL declaration.

dlls/msxml3/tests/schema.c

@@ -30,6 +30,7 @@
 #undef CLSID_DOMDocument
 #include "msxml2did.h"
 #include "dispex.h"
+#include "cguid.h"
 
 #include "wine/test.h"
 

dlls/rpcrt4/ndr_contexthandle.c

@@ -22,6 +22,7 @@
 #include "ndr_misc.h"
 #include "rpc_assoc.h"
 #include "rpcndr.h"
+#include "cguid.h"
 
 #include "wine/debug.h"
 #include "wine/list.h"

dlls/setupapi/devinst.c

@@ -37,6 +37,7 @@
 #include "winioctl.h"
 #include "rpc.h"
 #include "rpcdce.h"
+#include "cguid.h"
 
 #include "setupapi_private.h"
 

dlls/setupapi/tests/devinst.c

@@ -31,6 +31,7 @@
 #include "devpkey.h"
 #include "setupapi.h"
 #include "cfgmgr32.h"
+#include "cguid.h"
 
 #include "wine/heap.h"
 #include "wine/test.h"

include/guiddef.h

@@ -167,6 +167,4 @@ inline bool operator!=(const GUID& guidOne, const GUID& guidOther)
 }
 #endif
 
-extern const IID GUID_NULL;
-
 #endif /* _GUIDDEF_H_ */