// cfg is nil. This is safe to call even if cfg is in active use by a TLS
// client or server.
//
// cloneTLSConfig should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
//   - github.com/searKing/golang
//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:linkname cloneTLSConfig