Ensure that this header includes xmldoc.h, since it depends on it.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@197335 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/agi.h

@@ -28,6 +28,7 @@ extern "C" {
 #endif
 
 #include "asterisk/cli.h"
+#include "asterisk/xmldoc.h"
 #include "asterisk/optional_api.h"
 
 typedef struct agi_state {