Add From coqutil to imports

[tchajed]

Perennial builds coqutil with a _CoqProject that uses -Q coqutil/src coqutil rather than -R, which makes these From coqutil qualifiers required.

We could change Perennial but I think these are good style anyway and this is the first time this has been a problem.

[samuelgruetter]

I'm surprised we don't use -Q in our own (generated) _CoqProject, which would have caught these non-qualified imports (probably introduced in #127). So I pushed the -R to -Q change right to the branch of this PR

[tchajed]

Awesome, thanks for the fast response and fixing the underlying issue, too.