Make it impossible to initialize AutoHBITMAP after construction.

Add default ctor and Init() method to wxMSW private AutoHBITMAP class.

This doesn't change anything for now but will be used by an upcoming commit.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65958 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/private.h

@@ -541,8 +541,13 @@ public:
 class AutoHBITMAP : private AutoGDIObject
 {
 public:
+    AutoHBITMAP()
+        : AutoGDIObject() { }
+
     AutoHBITMAP(HBITMAP hbmp) : AutoGDIObject(hbmp) { }
 
+    void Init(HBITMAP hbmp) { InitGdiobj(hbmp); }
+
     operator HBITMAP() const { return (HBITMAP)GetObject(); }
 };