Fix parked call performing a DTMF blind transfer after being retrieved.

Fix parked call performing a DTMF blind transfer after being retrieved.

When a parked call was retrieved from the parking lot, it could not do a
blind transfer because it caused the involved calls to be hung up
unconditionally.

* Made the ParkedCall application return the ast_bridge_call() return
value.

(closes issue ABE-2862)
Reported by: Vlad Povorozniuc
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Merged revisions 368567 from http://svn.asterisk.org/svn/asterisk/branches/1.8

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/10@368568 65c4cc65-6c06-0410-ace0-fbb531ad65f3