Include path to ghc-pkg in `ghc --info`
haskell/ghcup-hs#73 notices that build tools currently have no reliable way of identifying the
hc-pkg executable associated with a give compiler. This is especially problematic when compilers are installed with version suffixes.
Cabal currently uses a variety of heuristics to identify
ghc-pkg, but this is not hard to break (as pointed out in haskell/ghcup-hs#73).
I suggest that we include an
hspkg-path entry in the
ghc --info output for use by build tools.