Currently, ghc-in-ghci is hard-coded to only support
the installation path of the make-based build system. There isn't
a fundamental reason why this must be the case, however—it's just a
matter of communicating which directories to look into.
For the time being, I've hacked utils/ghc-in-ghci/run.sh to just
check the default Hadrian installation path in addition to the make
one. Disclaimer: I'm not well-versed in bash-fu, so it's possible
that there is a better way to accomplish what I'm setting out to do.