Do not create redundant subtractions in toScalExp.
Do not create redundant subtractions in toScalExp.

mrakgr/futhark,HIPERFIT/futhark,HIPERFIT/futhark,diku-dk/futhark,HIPERFIT/futhark,diku-dk/futhark,diku-dk/futhark,ihc/futhark,diku-dk/futhark,mrakgr/futhark,mrakgr/futhark,ihc/futhark,ihc/futhark,diku-dk/futhark,CulpaBS/wbBach