fix killing of rewritten loads

OP_LOADs removed by rewrite_load_instruction() had their ->bb simply
set to NULL the usage of its operand was not adjusted.

Fix that by calling kill_instruction().

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Christopher Li <sparse@chrisli.org>
2 files changed