base: Refactor Show ErrorCall instance into proper ShowS style
base: Refactor Show ErrorCall instance into proper ShowS style

Test Plan: Validate

Reviewers: hvr, dfeuer

Reviewed By: dfeuer

Subscribers: dfeuer, rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4304

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