res_pjsip: ami: Fix error in AMI output when an endpoint has no transport

res_pjsip: ami: Fix error in AMI output when an endpoint has no transport

When no transport is associated to an endpoint, the AMI output for
PJSIPShowEndpoint indicates an error instead of silently ignoring the
missing transport.

This patch causes the error to appear only if a transport was specified
on the endpoint and the transport doesn't exist.  It also fixes an issue
with counting the objects that were actually found.

ASTERISK-24161 #close
ASTERISK-24331 #close
Tested by: George Joseph
Review: https://reviewboard.asterisk.org/r/3998/

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/12@423282 65c4cc65-6c06-0410-ace0-fbb531ad65f3