We need to release the SELinux label when we destroy the sandbox

This will release the MCS Label to be used again.  Only do this if we
don't have another sandbox using the same label.

Also vendor in the latest selinux go bindings, which fixes a leak and
properly reserves the SELinux label we are going to use.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

vendor/github.com/opencontainers/selinux/go-selinux/label/label_selinux.go

@@ -49,8 +49,10 @@ func InitLabels(options []string) (string, string, error) {
 				mcon[con[0]] = con[1]
 			}
 		}
+		_ = ReleaseLabel(processLabel)
 		processLabel = pcon.Get()
 		mountLabel = mcon.Get()
+		_ = ReserveLabel(processLabel)
 	}
 	return processLabel, mountLabel, nil
 }