chordal: Remove dead assignment.

ir/be/bechordal_common.c

@@ -122,7 +122,7 @@ void create_borders(ir_node *block, void *env_ptr)
 
 ir_node *pre_process_constraints(be_chordal_env_t *env, be_insn_t **the_insn)
 {
-	be_insn_t *insn = *the_insn;
+	be_insn_t *const insn = *the_insn;
 
 	/*
 	 * Make the Perm, recompute liveness and re-scan the insn since the
@@ -141,7 +141,7 @@ ir_node *pre_process_constraints(be_chordal_env_t *env, be_insn_t **the_insn)
 	 * the live sets may change.
 	 */
 	obstack_free(&env->obst, insn);
-	*the_insn = insn = be_scan_insn(env, irn);
+	*the_insn = be_scan_insn(env, irn);
 
 	/* Copy the input constraints of the irn to the Perm as output
 	 * constraints. Succeeding phases (coalescing) will need that. */