ralloc: Delete autofree handling.

ralloc: Delete autofree handling.

There was exactly one user of this, and I just removed it.

It also accessed an implicit global context, with no locking.  This
meant that it was only safe if all callers of ralloc_autofree_context()
held the same lock...which is a pretty terrible thing for a utility
library to impose.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>