Give stdout when running "ghc-pkg describe" errors
Give stdout when running "ghc-pkg describe" errors

When using hsenv, I was encountering a scenario where I was only
getting "ghc-pkg describe error:".  With this added stdout, I
additionally get "ghc-pkg wrapper: Couldn't find real ghc-pkg program".

fpco/fay,beni55/fay,fpco/fay,beni55/fay