REPEAT_LT : (list_tactic -> list_tactic)
Repeatedly applies a list-tactic until it fails.
The list-tactic REPEAT_LT ltac is a list-tactic which applies ltac
to a goal list, and while it succeeds,
continues applying it to the resulting subgoal list.
The application of REPEAT_LT to a list-tactic never fails,
and neither does the composite list-tactic,
even if the basic list-tactic fails immediately.