endless recursion when avp is not is found in the dictionary

[MuhammadTalhaRao]

In "/diam/dict/util.go" we try to find an avp and if we don't find it in its specific application and base dictionary the we get stuck in an endless loop.
i fixed this issue for my library by adding a few checks but this issue need to fixed properly

if ok {
	return avp, nil
} else if appid != 0 {
	parentAppId, isScoppedApp := parentAppIds[appid]
	if isScoppedApp {
		// Try searching 'parent' dictionary
		appid = parentAppId
	} else {
		// Try searching the base dictionary.
		appid = 0
	}
	goto retry
} else {
          // here the endless recursion occurs

	if codeU32, isUint32 := code.(uint32); isUint32 {
		avp, err = p.FindAVP(origAppID, codeU32)
		if err != nil {
			return MakeUnknownAVP(origAppID, codeU32, vendorID), err
		}

		return avp, nil
	}
}