Cleanup: rename old -> versioning

The term 'old' isn't very meaningful, follow naming for existing
code that updates data.

source/blender/editors/gpencil/CMakeLists.txt

@@ -50,8 +50,8 @@ set(SRC
 	gpencil_fill.c
 	gpencil_interpolate.c
 	gpencil_merge.c
-	gpencil_old.c
 	gpencil_ops.c
+	gpencil_ops_versioning.c
 	gpencil_paint.c
 	gpencil_primitive.c
 	gpencil_select.c