Fix bug #66286: Incorrect object comparison with inheritance

std_compare_objects immidiately returned 0 if the property tables
of both objects contain NULL at some index. Thus it would report
objects as equal even though properties following after that
differ.
Merge branch 'PHP-5.4' into PHP-5.5
Merge branch 'PHP-5.5' into PHP-5.6
Merge branch 'PHP-5.6'