Improved feature limits interval hook implementaion.

Improved feature limits interval hook implementaion.

* Fixed feature limits to not use special members of struct
ast_bridge_features.

* Fixed memory leak in off nominal paths of bridge_builtin_set_limits().

* Fixed off nominal path in ast_bridge_features_limits_construct() freeing
unallocated memory if it was not called by bridge_builtin_set_limits().

* Made bridge_builtin_interval_features.so unloadable.

* Simplified parking's use of its duration interval hook.

* Made BridgeWait S option not depend upon another module being loaded.

(closes issue ASTERISK-22107)
Reported by: Matt Jordan

Review: https://reviewboard.asterisk.org/r/2701/

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@395559 65c4cc65-6c06-0410-ace0-fbb531ad65f3