Add separate console socket

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

libcontainer/console_linux.go

@@ -7,6 +7,12 @@ import (
 	"unsafe"
 )
 
+func ConsoleFromFile(f *os.File) Console {
+	return &linuxConsole{
+		master: f,
+	}
+}
+
 // newConsole returns an initialized console that can be used within a container by copying bytes
 // from the master side to the slave that is attached as the tty for the container's init process.
 func newConsole() (Console, error) {