Fix OSS-Fuzz #439125710: Pipe cannot be used in write context

Author: ndossche

Zend/tests/pipe_operator/oss_fuzz_439125710.phpt

@@ -0,0 +1,8 @@
+--TEST--
+OSS-Fuzz #439125710 (Pipe cannot be used in write context)
+--FILE--
+<?php
+list(y|>y)=y;
+?>
+--EXPECTF--
+Fatal error: Can't use function return value in write context in %s on line %d

Zend/zend_compile.c

@@ -3365,7 +3365,7 @@ static void zend_compile_list_assign(
 
 static void zend_ensure_writable_variable(const zend_ast *ast) /* {{{ */
 {
-	if (ast->kind == ZEND_AST_CALL) {
+	if (ast->kind == ZEND_AST_CALL || ast->kind == ZEND_AST_PIPE) {
 		zend_error_noreturn(E_COMPILE_ERROR, "Can't use function return value in write context");
 	}
 	if (