Update runc to 593914b8bd5448a93f7c3e4902a03408b6d

This bumps runc to the newest version as of this date.

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

vendor/github.com/opencontainers/runc/libcontainer/user/lookup_unix.go

@@ -5,6 +5,8 @@ package user
 import (
 	"io"
 	"os"
+
+	"golang.org/x/sys/unix"
 )
 
 // Unix-specific path to the passwd and group formatted files.
@@ -28,3 +30,17 @@ func GetGroupPath() (string, error) {
 func GetGroup() (io.ReadCloser, error) {
 	return os.Open(unixGroupPath)
 }
+
+// CurrentUser looks up the current user by their user id in /etc/passwd. If the
+// user cannot be found (or there is no /etc/passwd file on the filesystem),
+// then CurrentUser returns an error.
+func CurrentUser() (User, error) {
+	return LookupUid(unix.Getuid())
+}
+
+// CurrentGroup looks up the current user's group by their primary group id's
+// entry in /etc/passwd. If the group cannot be found (or there is no
+// /etc/group file on the filesystem), then CurrentGroup returns an error.
+func CurrentGroup() (Group, error) {
+	return LookupGid(unix.Getgid())
+}