Changes from chan_dahdi that did not make it into sig_pri.

*  Moved SUPPORT_USERUSER to sig_pri.c
*  Fix PRI_DEADLOCK_AVOIDANCE parameter.
*  Whitespace changes.
*  Added missing unlock in pri_dchannel():PRI_EVENT_RING case.
*  Balanced curly braces.
*  ast_debug/ast_log changes from chan_dahdi.
*  sig_pri_indicate() should default to return -1 if the indication is not
handled.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@210154 65c4cc65-6c06-0410-ace0-fbb531ad65f3