HSA: remove image* builtins from the kernel library for now.
HSA: remove image* builtins from the kernel library for now.

The host versions were being built, and there is no image support in
pocl ATM at all.

rjodin/pocl,dsandersimgtec/pocl,rjodin/pocl,pocl/pocl,vkorhonen/pocl,jrprice/pocl,pavanky/pocl,dsandersimgtec/pocl,Oblomov/pocl,franz/pocl,Oblomov/pocl,franz/pocl,rjodin/pocl,vkorhonen/pocl,pocl/pocl,pocl/pocl,dsandersimgtec/pocl,Oblomov/pocl,pavanky/pocl,pocl/pocl,Oblomov/pocl,jrprice/pocl,vkorhonen/pocl,pavanky/pocl,franz/pocl,dsandersimgtec/pocl,franz/pocl,franz/pocl,Oblomov/pocl,jrprice/pocl,rjodin/pocl,pocl/pocl,jrprice/pocl,pavanky/pocl,vkorhonen/pocl