Merge branch 'PHP-7.4'

* PHP-7.4:
  Fix #78633: Heap buffer overflow (read) in mb_eregi

Author: smalyshev

ext/mbstring/tests/bug78633.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Bug #78633 (Heap buffer overflow (read) in mb_eregi)
+--SKIPIF--
+<?php
+if (!extension_loaded('mbstring')) die('skip mbstring extension not available');
+if (!function_exists('mb_eregi')) die('skip mb_eregi function not available');
+?>
+--FILE--
+<?php
+var_dump(mb_eregi(".+Isssǰ", ".+Isssǰ"));
+?>
+--EXPECT--
+bool(false)