Delete global PHP object on shutdown
Delete global PHP object on shutdown

Deleting the global object implicitly deletes all the properties,
i.e. PHP objects we previously attached to it (and for which we
increased the reference counter).

Since the following idle notifications trigger the weak callbacks,
the references on the PHP objects are finally decreased.

stesie/v8js,php/pecl-languages-v8js,uniconstructor/v8js,rosmo/v8js,rosmo/v8js,php/pecl-languages-v8js,dayed/v8js,dayed/v8js,stesie/v8js,preillyme/v8js,dayed/v8js,ABaldwinHunter/v8js-clone,zzhh9857/v8js,uniconstructor/v8js,uniconstructor/v8js,phpv8/v8js,phpv8/v8js,preillyme/v8js,zzhh9857/v8js,stesie/v8js,ABaldwinHunter/v8js-clone,uniconstructor/v8js,phpv8/v8js,rosmo/v8js,php/pecl-languages-v8js,dayed/v8js,preillyme/v8js,stesie/v8js,php/pecl-languages-v8js,ABaldwinHunter/v8js-clone,ABaldwinHunter/v8js-clone,preillyme/v8js,rosmo/v8js,zzhh9857/v8js,zzhh9857/v8js