Fix test gc_029_zts.phpt

In ZTS the default properties are duplicated (instead of copied),
so the array has one lower RC than on NTS and as such gets destroyed
during GC, increasing the cycle count by 3. PHP 5.6 didn't always
copy default properties on ZTS, which is where the difference comes
from.
Merge branch 'master' of git://github.com/php/php-src