Make http://php.net/socket_select have optional non-references

[TysonAndre]

Note:
Due a limitation in the current Zend Engine it is not possible to pass a constant modifier like NULL directly as a parameter to a function which expects this parameter to be passed by reference. Instead use a temporary variable or an expression with the leftmost member being a temporary variable:

See array_multisort and ZEND_ACC_PREFER_REFERENCE