[RFC] Merge criteria for tree-ssa

[Richard Kenner]

  - Verify function and file-level documentation to make sure
    it's up-to-date.

And that it meets documentation standards, which means independently
describing what algoriths are used, defining the terms that are used, etc.
I sent email about this a while ago and everybody agreed these were already
required by our documentation standards.

Every function also needs documentation about what it's supposed to do and
what the parameters mean.