Change uniqueness rule for unzip.
Change uniqueness rule for unzip.

The resulting arrays are now as unique as the input arrays.

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