Merged revisions 135747 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.4

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r135747 | tilghman | 2008-08-05 16:34:46 -0500 (Tue, 05 Aug 2008) | 9 lines

In a conversion to use ast_strlen_zero, the meaning of the flag IAX_HASCALLERID
was perverted.  This change reverts IAX2 to the original meaning, which was,
that the callerid set on the client should be overridden on the server, even if
that means the resulting callerid is blank.  In other words, if you set
"callerid=" in the IAX config, then the callerid should be overridden to blank,
even if set on the client.  Note that there's a distinction, even on realtime,
between the field not existing (NULL in databases) and the field existing, but
set to blank (override callerid to blank).

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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@135748 65c4cc65-6c06-0410-ace0-fbb531ad65f3