Define LVS_EX_DOUBLEBUFFER ourselves if SDK headers don't do it

This should fix compilation with MinGW after the changes of
2a6e411887 which started using this style.

See #17177.

include/wx/msw/missing.h

@@ -184,6 +184,10 @@
     #define LVS_EX_SUBITEMIMAGES 0x00000002
 #endif
 
+#ifndef LVS_EX_DOUBLEBUFFER
+    #define LVS_EX_DOUBLEBUFFER 0x00010000
+#endif
+
 #ifndef HDN_GETDISPINFOW
     #define HDN_GETDISPINFOW (HDN_FIRST-29)
 #endif