Put private IFileDialog helpers into an anonymous namespace

Don't use extern linkage for these private helpers.

No real changes.

src/msw/dirdlg.cpp

@@ -88,6 +88,9 @@ wxIMPLEMENT_CLASS(wxDirDialog, wxDialog);
 
 #if wxUSE_IFILEOPENDIALOG
 
+namespace
+{
+
 // helper functions for wxDirDialog::ShowIFileOpenDialog()
 bool InitIFileOpenDialog(const wxString& message, const wxString& defaultPath,
                          int options,
@@ -96,6 +99,8 @@ bool GetPathsFromIFileOpenDialog(const wxCOMPtr<IFileOpenDialog>& fileDialog, bo
                                  wxArrayString& paths);
 bool ConvertIShellItemToPath(const wxCOMPtr<IShellItem>& item, wxString& path);
 
+} // anonymous namespace
+
 #endif // #if wxUSE_IFILEOPENDIALOG
 
 // callback used in wxDirDialog::ShowSHBrowseForFolder()
@@ -302,6 +307,9 @@ int wxDirDialog::ShowIFileOpenDialog(WXHWND owner)
 // private functions
 // ----------------------------------------------------------------------------
 
+namespace
+{
+
 // helper function for wxDirDialog::ShowIFileOpenDialog()
 bool InitIFileOpenDialog(const wxString& message, const wxString& defaultPath,
                          int options,
@@ -475,6 +483,8 @@ bool ConvertIShellItemToPath(const wxCOMPtr<IShellItem>& item, wxString& path)
     return true;
 }
 
+} // anonymous namespace
+
 #endif // wxUSE_IFILEOPENDIALOG
 
 // callback used in wxDirDialog::ShowSHBrowseForFolder()