Fix double-usage of unique name generator.
Fix double-usage of unique name generator.

This was a pretty nasty one to find.

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