Fix build on amd64/solaris.
Fix build on amd64/solaris.

Summary:
Commit 71fcc4c096ec0 breaks the 64bit build on Solaris 11. Solaris
is a multi-lib OS so both 32bit and 64bit binaries may  be run, but
by default it compiles to 32bit so that -m64 needs to be added in
the appropriate place when compiling for 64 bits.

Patch-from: Karel Gardas <karel.gardas@centrum.cz>

Reviewers: kgardas, austin

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D733

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