Make ghc.mk compatible with pedantic /bin/sh impls
Make ghc.mk compatible with pedantic /bin/sh impls

This fixes `for`-loops introduced via
64761ce9a899954a12d8e3ae8b400c5ad9648137
which can result in `for i in ;` which some
`/bin/sh` implementations don't like.

nushio3/ghc,tjakway/ghcjvm,nushio3/ghc,GaloisInc/halvm-ghc,olsner/ghc,mettekou/ghc,vTurbine/ghc,gridaphobe/ghc,shlevy/ghc,sgillespie/ghc,mettekou/ghc,vikraman/ghc,mettekou/ghc,sdiehl/ghc,ezyang/ghc,snoyberg/ghc,nushio3/ghc,shlevy/ghc,sdiehl/ghc,GaloisInc/halvm-ghc,vTurbine/ghc,mettekou/ghc,vikraman/ghc,mcschroeder/ghc,gridaphobe/ghc,olsner/ghc,oldmanmike/ghc,gridaphobe/ghc,snoyberg/ghc,tjakway/ghcjvm,snoyberg/ghc,mettekou/ghc,olsner/ghc,snoyberg/ghc,shlevy/ghc,ezyang/ghc,snoyberg/ghc,nushio3/ghc,oldmanmike/ghc,shlevy/ghc,sdiehl/ghc,ezyang/ghc,vikraman/ghc,sdiehl/ghc,GaloisInc/halvm-ghc,ezyang/ghc,GaloisInc/halvm-ghc,oldmanmike/ghc,gridaphobe/ghc,sdiehl/ghc,oldmanmike/ghc,gridaphobe/ghc,vTurbine/ghc,shlevy/ghc,olsner/ghc,GaloisInc/halvm-ghc,mettekou/ghc,sgillespie/ghc,nushio3/ghc,sdiehl/ghc,sgillespie/ghc,ezyang/ghc,mcschroeder/ghc,tjakway/ghcjvm,tjakway/ghcjvm,sgillespie/ghc,vikraman/ghc,nushio3/ghc,shlevy/ghc,mcschroeder/ghc,snoyberg/ghc,GaloisInc/halvm-ghc,ezyang/ghc,olsner/ghc,gridaphobe/ghc,oldmanmike/ghc,vTurbine/ghc,sgillespie/ghc,mcschroeder/ghc,shlevy/ghc,olsner/ghc,sdiehl/ghc,tjakway/ghcjvm,vikraman/ghc,vTurbine/ghc,vikraman/ghc,oldmanmike/ghc,sgillespie/ghc,mcschroeder/ghc,snoyberg/ghc,gridaphobe/ghc,oldmanmike/ghc,mcschroeder/ghc,nushio3/ghc,tjakway/ghcjvm,vTurbine/ghc,mettekou/ghc,vTurbine/ghc,mcschroeder/ghc,vikraman/ghc,olsner/ghc,GaloisInc/halvm-ghc,ezyang/ghc,sgillespie/ghc,tjakway/ghcjvm