Stasis_channels: Resolve unfinished Dials when doing masquerades

Masquerades into channels that are in the dialing state don't end their dial
and this goes against the model for things like CDRs and generating Dial end
manager actions and such.

ASTERISK-24237 #close
Reported by: Richard Mudgett
Review: https://reviewboard.asterisk.org/r/3990/


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@423525 f38db490-d61c-443f-a65b-d21fe96a405b