daemon: Refactor waiting for a TunTap device to exist.
daemon: Refactor waiting for a TunTap device to exist.

This should also fix an issue that caused excessive startup delay.
eiginn/coreemu,abn/coreemu,abn/coreemu,D3f0/coreemu,D3f0/coreemu,abn/coreemu,D3f0/coreemu,cudadog/coreemu,eiginn/coreemu,cudadog/coreemu,cudadog/coreemu,eiginn/coreemu