[profile-stdlib] PATCH: Add three diagnostics and implement cost factor parameterization

[Benjamin Kosnik]

> Can this still make it to 4.5, given that it affects only the profile
> mode?  If so, could you review it as a patch to trunk instead of
> branch?  There are no other changes on the profile-stdlib branch since
> the last merge to trunk, except for very minor fixes.

I'd be in favor of putting the cost factor parameterization in, since
that can change usage and it's definitely better to do this before first
public release.

Some of the simpler diagnostics for list-to-vector and list-to-slist
seem more likely to me.

-benjamin