Initialize variables that we attempt to free later.

(closes issue #16302)
 Reported by: yahsyn
 Patches: 
       20091124__issue16302.diff.txt uploaded by tilghman (license 14)
 Tested by: yahsyn


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@238754 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_agi.c

@@ -1235,6 +1235,7 @@ static enum agi_result launch_asyncagi(struct ast_channel *chan, char *argv[], i
 	async_agi.ctrl = fds[1];
 	async_agi.audio = -1; /* no audio support */
 	async_agi.fast = 0;
+	async_agi.speech = NULL;
 
 	/* notify possible manager users of a new channel ready to
 	   receive commands */