Fix PCH-less build

Add missing header to fix compilation after changes of
b1fad4da44 (see #17640).

src/msw/clipbrd.cpp

@@ -37,6 +37,7 @@
     #include "wx/intl.h"
     #include "wx/log.h"
     #include "wx/dataobj.h"
+    #include "wx/dcmemory.h"
 #endif
 
 #if wxUSE_METAFILE