Update unreachable blocks.

Author: dstogov

ext/opcache/Optimizer/dfa_pass.c

@@ -172,6 +172,9 @@ static void zend_ssa_remove_nops(zend_op_array *op_array, zend_ssa *ssa)
 				new_opline = op_array->opcodes + target - 1;
 				zend_optimizer_migrate_jump(op_array, new_opline, opline);
 			}
+		} else {
+			b->start = target;
+			b->len = 0;
 		}
 	}