[Yhc] yhc build failure -- possible missing dependency

[Eric Sessoms]

Just pulled the latest YHC this morning and got:

> YHC_build(["src/packages/yhc-base-1.0/Data/Set.hbc"],
> ["src/packages/yhc-base-1.0/Data/Set.hs"])
> inst/bin/yhc -cpp -c src/packages/yhc-base-1.0/Data/Set.hs
> Warning: Can't find file "Typeable.h" in directories
>         /home/eric/projects/yhc/src/packages/yhc-base-1.0/Data
>         .
>   Asked for by: /home/eric/projects/yhc/src/packages/yhc-base-1.0/Data/Set.hs  at line 553 col 1
> yhc: Error: File not found, Data.List
> Reason: imported from Data.Set
> Looked in:
>   /home/eric/projects/yhc/src/packages/yhc-base-1.0/
>   .
>   /home/eric/projects/yhc/inst/lib/yhc/packages/yhc-base/1.0

Building List by hand made it happy, so I'm guessing it's some sort of
scons-thing.

Eric