Switch to enqueue_copy for scalar operations.
Switch to enqueue_copy for scalar operations.

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