Use int instead of wxWindowID in wxNewId() and friends.

The functions are available in wxBase builds too, but wx/windowid.h
isn't. Rather than always including that header, just use int, for which
wxWindowID is a typedef. This keeps the functions available in wxBase
for compatibility and is consistent with how IDs are handled in other
parts of wxBase, particularly wxEvent.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74486 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/utils.h

@@ -459,7 +459,7 @@ int wxFindMenuItemId(wxFrame* frame, const wxString& menuString,
 
     @header{wx/utils.h}
 */
-wxWindowID wxNewId();
+int wxNewId();
 
 /**
     Ensures that Ids subsequently generated by wxNewId() do not clash with the
@@ -467,7 +467,7 @@ wxWindowID wxNewId();
 
     @header{wx/utils.h}
 */
-void wxRegisterId(wxWindowID id);
+void wxRegisterId(int id);
 
 /**
     Opens the @a document in the application associated with the files of this