memops: we can kill addresses unconditionally

In rewrite_load_instruction(), if the load instruction is converted
into a phi-node, its address is then no more used and must be removed.

However, this is only done when this address is not a symbol.
This was explicitly done in the following commit because of the problem
of removing an element from the usage list while walking this list:
   602f6b6 ("Leave symbol pseudo usage intact when doing phi-node conversion.")

But currently rewrite_load_instruction() is only used during memops
simplification where the usage list is not walked.

So, kill the address' usage unconditionally.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>

memops.c

@@ -45,9 +45,7 @@ static void rewrite_load_instruction(struct instruction *insn, struct pseudo_lis
 	goto end;
 
 complex_phi:
-	/* We leave symbol pseudos with a bogus usage list here */
-	if (insn->src->type != PSEUDO_SYM)
-		kill_use(&insn->src);
+	kill_use(&insn->src);
 	insn->opcode = OP_PHI;
 	insn->phi_list = dominators;