PHPC-1092: Don't reset hash on successive get_properties calls

[jmikola]

https://jira.mongodb.org/browse/PHPC-1092

This removes a call to zend_hash_clean() on successive calls to a BSON object's get_properties handler, which can lead to an infinite loop when iterating the object's properties with foreach on PHP 7.x.

For historical reference, the original call to zend_hash_clean() was introduced in ad1f3f0 for #607 (PHPC-939).

Note: I've only added tests for BSON classes that have a custom get_properties handler and utilize the PHONGO_GET_PROPERTY_HASH_INIT_PROPS() macro. I do not recall why I originally added zend_clean_hash(), but I assume I was trying to be strict about not inheriting hash state from previous calls.

While testing this, I was surprised to find that iterating the object with foreach actually invokes get_properties multiple times. If I had to guess, the fact that zend_hash_clean() resets the hash pointer was causing foreach to never advance past the first property.

[derickr]

LGTM

[jmikola]

While testing this, I was surprised to find that iterating the object with foreach actually invokes get_properties multiple times. If I had to guess, the fact that zend_hash_clean() resets the hash pointer was causing foreach to never advance past the first property.

Indeed, ZEND_FE_FETCH_R does invoke the get_properties handler on each execution: https://github.com/php/php-src/blob/php-7.2.1/Zend/zend_vm_def.h#L5912