libdpkg: Add missing symbols to Versions script

lib/dpkg/libdpkg.Versions

@@ -164,6 +164,7 @@ LIBDPKG_PRIVATE {
 	informative;
 	copy_dependency_links;
 	pkg_sorter_by_name;
+	pkg_summary;
 
 	# Package list handling
 	pkg_list_new;
@@ -208,6 +209,7 @@ LIBDPKG_PRIVATE {
 
 	# Log based package on-disk database support
 	modstatdb_init;
+	modstatdb_is_locked;
 	modstatdb_lock;
 	modstatdb_unlock;
 	modstatdb_note;