segredomap: add example with invariant variable used in reduce
segredomap: add example with invariant variable used in reduce

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