Fix channel reference leak in ChanSpy.

* Fix next_channel() channel reference leak in ChanSpy.

(closes issue ASTERISK-19461)
Reported by: Irontec
Patches:
      app_chanspy_iteartor_next_unref.patch (license #6213) patch uploaded by Irontec

(issue ASTERISK-17515)
........

Merged revisions 357809 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 357810 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@357815 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_chanspy.c

@@ -748,8 +748,10 @@ redo:
 	}
 
 	if (!strncmp(ast_channel_name(next), "DAHDI/pseudo", pseudo_len)) {
+		ast_channel_unref(next);
 		goto redo;
 	} else if (next == chan) {
+		ast_channel_unref(next);
 		goto redo;
 	}