Fix memory leak in SCCP

Fixes oss-fuzz #42878

Author: dstogov

ext/opcache/Optimizer/sccp.c

@@ -1547,6 +1547,7 @@ static void sccp_visit_instr(scdf_ctx *scdf, zend_op *opline, zend_ssa_op *ssa_o
 						if (opline->opcode == ZEND_PRE_INC_OBJ
 								|| opline->opcode == ZEND_PRE_DEC_OBJ) {
 							SET_RESULT(result, &tmp2);
+							zval_ptr_dtor_nogc(&tmp1);
 						} else {
 							SET_RESULT(result, &tmp1);
 						}

ext/opcache/tests/opt/sccp_035.phpt

@@ -0,0 +1,17 @@
+--TEST--
+SCCP 035: memory leak
+--INI--
+opcache.enable=1
+opcache.enable_cli=1
+opcache.optimization_level=-1
+--FILE--
+<?php
+function test() {
+  $obj = new stdClass;
+  $obj->$b = ~$b = $a='';
+  $obj->$a--;
+}
+?>
+DONE
+--EXPECT--
+DONE