Fix tuple stuff usage on first-order transform.
Fix tuple stuff usage on first-order transform.

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