util/cmpx: delete now that we're using Go 1.22

Updates #11058

Change-Id: I09dea8e86f03ec148b715efca339eab8b1f0f644
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

derp/derphttp/derphttp_client.go

@@ -11,6 +11,7 @@ package derphttp
 
 import (
 	"bufio"
+	"cmp"
 	"context"
 	"crypto/rand"
 	"crypto/tls"
@@ -41,7 +42,6 @@ import (
 	"tailscale.com/tstime"
 	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
-	"tailscale.com/util/cmpx"
 )
 
 // Client is a DERP-over-HTTP client.
@@ -701,7 +701,7 @@ func (c *Client) dialNode(ctx context.Context, n *tailcfg.DERPNode) (net.Conn, e
 					// Start v4 dial
 				}
 			}
-			dst := cmpx.Or(dstPrimary, n.HostName)
+			dst := cmp.Or(dstPrimary, n.HostName)
 			port := "443"
 			if n.DERPPort != 0 {
 				port = fmt.Sprint(n.DERPPort)