On macOS, if a process already listens on 127.0.0.1:PORT, net.Listen() falls back
to IPv6 address ie minio will start listening on IPv6 address whereas another
(non-)minio process is listening on IPv4 of given port.
To avoid this error sutiation we check for port availability only for macOS.
Note: checkPortAvailability() tries to listen on given port and closes it.
It is possible to have a disconnected client in this tiny window of time.
For command line arguments we are currently following
- <node-1>:/path ... <node-n>:/path
This patch changes this to
- http://<node-1>/path ... http://<node-n>/path