properly cancel a Paginated Results operation in order to avoid protocol errors, fixes #10526
abandon ongoing paged search before starting a new one
abandond paged search only if PHP supports them
init a new paged search on read operations to satisfy OpenLDAP
make scrutinizer happy, very minor changes
Merge pull request #10527 from owncloud/fix-10526

properly cancel a Paginated Results operation in order to avoid protocol...