re-add the _BMCItem_ class for binary compatibility.

This was removed in hrev17147, because our implementation of BMenuItem
does not uses it anymore. However, we must keep it in order to properly
unarchive BMenuFields that were archived in BeOS.

One application that was crashing because of this is VNCViewer.

src/kits/interface/BMCPrivate.cpp

@@ -25,6 +25,38 @@
 static const float kPopUpIndicatorWidth = 13.0f;
 
 
+#if __GNUC__ == 2
+
+
+// This is kept only for binary compatibility with BeOS R5. This class was
+// used in their BMenuField implementation and we may come across some archived
+// BMenuField that needs it.
+class _BMCItem_: public BMenuItem {
+public:
+	_BMCItem_(BMessage* data);
+	static BArchivable* Instantiate(BMessage *data);
+};
+
+
+_BMCItem_::_BMCItem_(BMessage* data)
+	: BMenuItem(data)
+{
+
+}
+
+
+/*static*/ BArchivable*
+_BMCItem_::Instantiate(BMessage *data) {
+	if (validate_instantiation(data, "_BMCItem_"))
+		return new _BMCItem_(data);
+
+	return NULL;
+}
+
+
+#endif
+
+
 //	#pragma mark - _BMCFilter_