API: Account for PHP 7.2 change

API: Account for PHP 7.2 change

PHP 7.2 broke existing functionality in making count( null ) raise a
warning. So add tests for null all over the place, or change tests where
we know the value is null or an array (but not false, empty-string, or
0) to just cast to boolean.

Bug: T182004
Change-Id: Idfe23a07daa9f60eee72f2daf04304be87057a29