Updating of detail tabs besides list of tables works correctly again.

Had stopped working because the catalog now behaves a little different,
returning nullptr instead of an invalid element.

pglablib/PgAttribute.h

@@ -20,6 +20,7 @@ public:
 	int32_t typmod = -1;
 	bool notnull = false;
 	bool hasdef = false;
+	bool isdropped = false;
 	Oid collation = InvalidOid;
 	QString acl;
 	QString options;