test_cdr.c, test_cel.c: Correctly destroy created bridges.

* Fixed the test_cel_attended_transfer_bridges_link unit test to also
account for the local channel link being destroyed now that the bridges
are actually destroyed.

* Made CDR unit test use its own version of do_sleep() from the CEL unit
tests.
........

Merged revisions 406707 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@406710 65c4cc65-6c06-0410-ace0-fbb531ad65f3