Change the remove_on_pull flag on ast_bridge_hook to be a set of flags.

This change is used to make bridge hook removal more generic. This way,
depending on the circumstance, the appropriate bridge hooks may be
removed.



git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@390510 f38db490-d61c-443f-a65b-d21fe96a405b