Fix `ghc --make -fhpc` with imported lhs modules

Authored by thomie.

Description

Fix ghc --make -fhpc with imported lhs modules

See Note [Don't normalise input filenames] in
compiler/main/DriverPipeline.hs. Fixes Trac #2991.

Reviewers: austin

Differential Revision: https://phabricator.haskell.org/D701