EZC: fix ProxyArray compilation with ENABLE_ZEND_COMPAT=OFF

When ENABLE_ZEND_COMPAT is off:
* In zend-wrap-func.h, define zBoxAndProxy() as well as zend_wrap_func,
  since both are now referenced from outside ext_zend_compat
* Set ZVAL_PTR_DTOR to be a local empty function, to avoid a linker
  error.