WriteKernel code generation cleanup.
WriteKernel code generation cleanup.

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