futhark-mode.el: Add autoload pragma for use with package managers.
futhark-mode.el: Add autoload pragma for use with package managers.

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