res_xmpp: Buddies are always auto-registered when processing the roster

Due to a quirk in the configuration handling of res_xmpp, the 'autoregister'
setting was never actually processed. This was due to not properly copying
over the global settings to the client settings when applying the
configuration to the run-time object.

Review: https://reviewboard.asterisk.org/r/4496/

ASTERISK-14233
ASTERISK-24780 #close
Reported by: Simon Arlott
patches:
  asterisk-13.1.0-24780 uploaded by Simon Arlott (License 5756)
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Merged revisions 433395 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 433396 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@433397 65c4cc65-6c06-0410-ace0-fbb531ad65f3