Another GHC 7.8 fix.
Another GHC 7.8 fix.

ihc/futhark,ihc/futhark,HIPERFIT/futhark,ihc/futhark,diku-dk/futhark,diku-dk/futhark,diku-dk/futhark,diku-dk/futhark,diku-dk/futhark,HIPERFIT/futhark,HIPERFIT/futhark