Add some dummy memmove/memcopy definitions for kernels.
Add some dummy memmove/memcopy definitions for kernels.

This is nowhere near the right thing, but it will do for now.

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