Fix coaslescing case for multidimensional ReduceKernel map-outs.
Fix coaslescing case for multidimensional ReduceKernel map-outs.

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