abel and progress

Stream: mathlib4

[Patrick Massot]

I just opened #8482 which fixes fail_if_no_progress (one of the three usual fixes). But what would be even better would be to fix abel and abel_nf so that you don't need to wrap them up in fail_if_no_progress @Mario Carneiro.

[Scott Morrison]

@Patrick Massot #8487

[Scott Morrison]

See also lean4#2909, a bad doc-string which I noticed while debugging this.