As per bug 8859 (Add option to revert old ChanIsAvail() with 's' option...

As per bug 8859 (Add option to revert old ChanIsAvail() with 's' option behavior), this update makes the 't' option available, which calls ast_parse_device_state instead of ast_device_state. This option will not dive into the channel driver to find the status of the device (which could be good if sip devicestate isn't returning full status, for various reasons).

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@52086 65c4cc65-6c06-0410-ace0-fbb531ad65f3