* tree-wide: Replace `CHECK_NULL_PATH()` by `zend_char_has_nul_byte()`
The former is a direct alias of the latter with a more explicit name and the
former is explicitly documented as a “compatibility” alias.
* tree-wide: Replace `CHECK_ZVAL_NULL_PATH()` by its definition
The former is explicitly documented as a “compatibility” alias.
* zend_API: Remove `CHECK*NULL_PATH`
The `CHECK_ZVAL_NULL_PATH()` macro is unsafe, because it implicitly assumes
that the given `zval*` is `IS_STRING`.
Based on a GitHub search there does not seem to be any user outside of PHP, all
hits were just forks / copies of php-src.
6da93a86f2