* zend_language_parser: Support every argument syntax for `clone()`
* zend_language_parser: Adjust `clone()` grammar to avoid conflicts
* zend_language_parser: Add explanatory comment for `clone_argument_list`
Second pass through `Zend/tests/bug*` to organize the tests.
Move tests to existing sub directories, and create some new sub directories:
* `ArrayAccess`
* `autoload`
* `clone`
* `serialize` (also covers `unserialize()`)
* `switch`
Work towards GH-15631
Tim Düsterhus