The previous set of not-cancel.h headers (prior to the commit
2fbdf5339aaeaa423bd661524f7ec7af41fa2606) did not require the
arch to define nocancel entry points, so ia64 never did.
However, after the various files were merged, it became a hard
requirement for arches which mean ia64 failed to build.
Here we add dedicated entry points. It'd be nice to merge
with the existing stubs like other arches do, but the ia64
asm does not lend itself to interleaving of functions. If
someone has a suggestion on merging these, that'd be great,
but at least now we build & pass tests again.
