Reverting some changes in CExprAnn.

I thought about collapsing both the type and the coersion constructors
to a single AnnTy, but this requires more changes than I am willing to
write right now. Maybe I'll come back to this later.
fixup! Moving to a single constructor type scheme.
Getting AnaRelevance to compile.

For now, this is just a minor fix to get the file to compile properly.
Still need to implement properly.
Getting OptimizeStrictness to compile.

Again, just a minor fix. This should work until we get to the point
of actually using the strictness information.

Due to the different ways Atze and I encode strictness informaion (he
uses coersion and I'm not sure if I'll follow the same path).