Fixes port collision issue on use of --publish-all

The function which generates and assigns a random
port number for the --publish-all functionality
was not properly marking some ports as "used".
In very rare occasions this can cause a randomly
"generated" port to be used twice creating an
impossible container configuration.

Signed-off-by: telday <ellis.wright@cyberark.com>

pkg/specgen/generate/ports.go

@@ -311,6 +311,8 @@ func ParsePortMapping(portMappings []types.PortMapping, exposePorts map[uint16][
 						return nil, err
 					}
 					portMappings = append(portMappings, p)
+					// Mark this port as used so it doesn't get re-generated
+					allPorts[p.HostPort] = true
 				} else {
 					newProtocols = append(newProtocols, protocol)
 				}