discovery: set proper flag within createChanAnnouncement
discovery: set proper flag within createChanAnnouncement

In this commit, we fix an existing bug within the
createChanAnnouncement function. Before we would set the flag to be 0,
or 1 depending on which edge it was. This was incorrect as since then
additional flags have been defined. We now properly set the entire
flag, rather than taking a shortcut. With this, we’ll properly
advertise all ChannelUpdate announcements.

LightningNetwork/lnd,aakselrod/lnd,aakselrod/lnd,LightningNetwork/lnd