Switch to new vendor directory layout

Fixes #113

Signed-off-by: Marcos Lilljedahl <marcosnils@gmail.com>

vendor/github.com/opencontainers/runc/libcontainer/system/setns_linux.go

@@ -0,0 +1,40 @@
+package system
+
+import (
+	"fmt"
+	"runtime"
+	"syscall"
+)
+
+// Via http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=7b21fddd087678a70ad64afc0f632e0f1071b092
+//
+// We need different setns values for the different platforms and arch
+// We are declaring the macro here because the SETNS syscall does not exist in th stdlib
+var setNsMap = map[string]uintptr{
+	"linux/386":     346,
+	"linux/arm64":   268,
+	"linux/amd64":   308,
+	"linux/arm":     375,
+	"linux/ppc":     350,
+	"linux/ppc64":   350,
+	"linux/ppc64le": 350,
+	"linux/s390x":   339,
+}
+
+var sysSetns = setNsMap[fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH)]
+
+func SysSetns() uint32 {
+	return uint32(sysSetns)
+}
+
+func Setns(fd uintptr, flags uintptr) error {
+	ns, exists := setNsMap[fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH)]
+	if !exists {
+		return fmt.Errorf("unsupported platform %s/%s", runtime.GOOS, runtime.GOARCH)
+	}
+	_, _, err := syscall.RawSyscall(ns, fd, flags, 0)
+	if err != 0 {
+		return err
+	}
+	return nil
+}