Fixes to type conversion simplification.
Fixes to type conversion simplification.

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