Set PATH properly on AppVeyor.
Set PATH properly on AppVeyor.

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