In a93dc6cdb1 tryUpgradeToBatchingConn()
moved to build tag gated files, but the runtime.GOOS condition excluding
Android was removed unintentionally from batching_conn_linux.go. Add it
back.
Updates tailscale/corp#22348
Signed-off-by: Jordan Whited <jordan@tailscale.com>
This commit adds a batchingConn interface, and renames batchingUDPConn
to linuxBatchingConn. tryUpgradeToBatchingConn() may return a platform-
specific implementation of batchingConn. So far only a Linux
implementation of this interface exists, but this refactor is being
done in anticipation of a Windows implementation.
Updates tailscale/corp#21874
Signed-off-by: Jordan Whited <jordan@tailscale.com>
