Remove static allocator

We didn't even compile this file anymore
Remove zend_dynamic_array

This was introduced back in 2000 to test a new hashtable
implementation and is no longer used.
Fix tests/serialize/bug64146.phpt

The var hash now retains a reference to its elements, to ensure
that addresses are not reused.

Furthermore the var hash now only stores objects and references
and directly uses their pointer as key, thus making serialization
about two times faster.