DynFlags: Expand $topdir in --info output
DynFlags: Expand $topdir in --info output

Test Plan: Try running nofib on Windows

Reviewers: Phyx

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D4222

shlevy/ghc,shlevy/ghc,sdiehl/ghc,ezyang/ghc,sdiehl/ghc,ezyang/ghc,sdiehl/ghc,ezyang/ghc,sdiehl/ghc,shlevy/ghc,sdiehl/ghc,ezyang/ghc,shlevy/ghc,sdiehl/ghc,ezyang/ghc,ezyang/ghc,shlevy/ghc,ezyang/ghc,shlevy/ghc,sdiehl/ghc,shlevy/ghc