Fix an issue that would cause a NewCallerID manager event to be generated

Fix an issue that would cause a NewCallerID manager event to be generated
before the channel's NewChannel event.  This was due to a somewhat recent
change that included using ast_set_callerid() where it wasn't before.  This
function should not be used in the channel driver "new" functions.
(issue #7654, fixed by me)

Also, fix a couple minor bugs in usecount handling.  chan_iax2 could have
increased the usecount but then returned an error.  The place where chan_sip
increased the usecount did not call ast_update_usecount()

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.2@38904 65c4cc65-6c06-0410-ace0-fbb531ad65f3