OpenCL copy fix.
OpenCL copy fix.

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