indexschemas should make summaries if they don't exist

[dericed]

This https://github.com/amiaopensource/ltopers/blob/master/indexschemas#L40 could presume the LTO_INDEX exists when perhaps it doesn't.

[retokromer]

@dericed Is this still an open issue? (Sorry, I haven’t follow carefully the developments in mm.)

[retokromer]

@dericed Is this still an open issue?