Do not swap operands in array addition

As we support constant array operands nowadays, the original check
didn't work anymore.

Author: nikic

Zend/tests/array_addition_not_commutative.phpt

@@ -0,0 +1,19 @@
+--TEST--
+Array addition is not commutative -- do not swap operands
+--FILE--
+<?php
+
+$array = [1, 2, 3];
+$array = [4, 5, 6] + $array;
+var_dump($array);
+
+?>
+--EXPECT--
+array(3) {
+  [0]=>
+  int(4)
+  [1]=>
+  int(5)
+  [2]=>
+  int(6)
+}

ext/opcache/Optimizer/pass3.c

@@ -106,7 +106,9 @@ void zend_optimizer_pass3(zend_op_array *op_array)
 						zend_uchar tmp_type = opline->op1_type;
 						znode_op tmp = opline->op1;
 
-						if (opline->opcode != ZEND_ADD || ZEND_OP1_TYPE(opline) == IS_CONST) {
+						if (opline->opcode != ZEND_ADD
+								|| (ZEND_OP1_TYPE(opline) == IS_CONST
+									&& Z_TYPE(ZEND_OP1_LITERAL(opline)) != IS_ARRAY)) {
 							/* protection from array add: $a = array + $a is not commutative! */
 							COPY_NODE(opline->op1, opline->op2);
 							COPY_NODE(opline->op2, tmp);