compiler/specialise: shut match_co up a bit
compiler/specialise: shut match_co up a bit

This stray pprTrace is quite annoying and makes our build logs a bit
bigger (hundreds of lines of occurrences), so we should probably just
get rid of it. Kept under DEBUG for future brave hackers.

Signed-off-by: Austin Seipp <austin@well-typed.com>

Reviewed By: thomie, nomeata

Differential Revision: https://phabricator.haskell.org/D934

siddhanathan/ghc,acowley/ghc,urbanslug/ghc,TomMD/ghc,anton-dessiatov/ghc,nushio3/ghc,GaloisInc/halvm-ghc,AlexanderPankiv/ghc,mcschroeder/ghc,vTurbine/ghc,oldmanmike/ghc,wxwxwwxxx/ghc,ezyang/ghc,ml9951/ghc,mfine/ghc,snoyberg/ghc,mfine/ghc,vTurbine/ghc,GaloisInc/halvm-ghc,urbanslug/ghc,urbanslug/ghc,TomMD/ghc,tjakway/ghcjvm,sdiehl/ghc,mfine/ghc,ghc-android/ghc,GaloisInc/halvm-ghc,siddhanathan/ghc,ezyang/ghc,mcschroeder/ghc,elieux/ghc,siddhanathan/ghc,oldmanmike/ghc,vikraman/ghc,wxwxwwxxx/ghc,nushio3/ghc,mcschroeder/ghc,acowley/ghc,ml9951/ghc,acowley/ghc,tjakway/ghcjvm,vikraman/ghc,urbanslug/ghc,ghc-android/ghc,anton-dessiatov/ghc,da-x/ghc,olsner/ghc,anton-dessiatov/ghc,mfine/ghc,vTurbine/ghc,siddhanathan/ghc,sdiehl/ghc,sgillespie/ghc,oldmanmike/ghc,ml9951/ghc,oldmanmike/ghc,vTurbine/ghc,tjakway/ghcjvm,gridaphobe/ghc,ezyang/ghc,AlexanderPankiv/ghc,ghc-android/ghc,nkaretnikov/ghc,urbanslug/ghc,sgillespie/ghc,mettekou/ghc,anton-dessiatov/ghc,oldmanmike/ghc,wxwxwwxxx/ghc,ezyang/ghc,ezyang/ghc,sdiehl/ghc,nkaretnikov/ghc,tjakway/ghcjvm,vTurbine/ghc,ezyang/ghc,ghc-android/ghc,nkaretnikov/ghc,nushio3/ghc,GaloisInc/halvm-ghc,gridaphobe/ghc,nkaretnikov/ghc,da-x/ghc,snoyberg/ghc,mfine/ghc,ghc-android/ghc,oldmanmike/ghc,shlevy/ghc,tjakway/ghcjvm,da-x/ghc,nkaretnikov/ghc,oldmanmike/ghc,olsner/ghc,sgillespie/ghc,GaloisInc/halvm-ghc,elieux/ghc,ghc-android/ghc,TomMD/ghc,mcschroeder/ghc,mettekou/ghc,elieux/ghc,vikraman/ghc,snoyberg/ghc,mfine/ghc,tjakway/ghcjvm,sdiehl/ghc,gridaphobe/ghc,gridaphobe/ghc,mettekou/ghc,sdiehl/ghc,olsner/ghc,acowley/ghc,mettekou/ghc,siddhanathan/ghc,shlevy/ghc,snoyberg/ghc,olsner/ghc,da-x/ghc,nushio3/ghc,TomMD/ghc,anton-dessiatov/ghc,TomMD/ghc,ml9951/ghc,wxwxwwxxx/ghc,mcschroeder/ghc,acowley/ghc,AlexanderPankiv/ghc,snoyberg/ghc,gridaphobe/ghc,acowley/ghc,GaloisInc/halvm-ghc,ghc-android/ghc,snoyberg/ghc,AlexanderPankiv/ghc,olsner/ghc,elieux/ghc,snoyberg/ghc,shlevy/ghc,olsner/ghc,vTurbine/ghc,mcschroeder/ghc,elieux/ghc,nushio3/ghc,AlexanderPankiv/ghc,da-x/ghc,ml9951/ghc,urbanslug/ghc,vikraman/ghc,vikraman/ghc,siddhanathan/ghc,shlevy/ghc,siddhanathan/ghc,wxwxwwxxx/ghc,vTurbine/ghc,shlevy/ghc,TomMD/ghc,shlevy/ghc,ezyang/ghc,nkaretnikov/ghc,GaloisInc/halvm-ghc,anton-dessiatov/ghc,urbanslug/ghc,sgillespie/ghc,mcschroeder/ghc,wxwxwwxxx/ghc,sgillespie/ghc,gridaphobe/ghc,mettekou/ghc,AlexanderPankiv/ghc,ml9951/ghc,sdiehl/ghc,mettekou/ghc,vikraman/ghc,mfine/ghc,TomMD/ghc,shlevy/ghc,anton-dessiatov/ghc,sgillespie/ghc,da-x/ghc,vikraman/ghc,nkaretnikov/ghc,tjakway/ghcjvm,mettekou/ghc,acowley/ghc,wxwxwwxxx/ghc,sgillespie/ghc,nushio3/ghc,ml9951/ghc,olsner/ghc,gridaphobe/ghc,sdiehl/ghc,elieux/ghc,elieux/ghc,ml9951/ghc,AlexanderPankiv/ghc,nushio3/ghc,da-x/ghc