ocp-index for 4.02

Thanks a lot to Peter Zotov (@whitequark) for the port. Proper compat will
be made upstream, but I really don't have time now, and this is
the easiest way to ocp-index on 4.02 for the users.
Fix ocp-build / typerex conflicts
Merge pull request #2565 from AltGr/ocp-index-402

Enable ocp-indent,index on 4.02