wxOS2 with Open Watcom: correct PCH usage, missing headers, warning fixes, source cleaning and other Watcom adjustements.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@34902 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/dynlib.h

@@ -23,10 +23,8 @@
 #include "wx/string.h"
 #include "wx/dynarray.h"
 
-// FIXME: can this go in private.h or something too??
 #if defined(__WXPM__) || defined(__EMX__)
-#define INCL_DOS
-#include <os2.h>
+#include "wx/os2/private.h"
 #endif
 
 #ifdef __WXMSW__