util/cmpx: remove code that's in the stdlib now

The cmpx.Compare function (and associated interface) are now available
in the standard library as cmp.Compare. Remove our version of it and use
the version from the standard library.

Updates #cleanup

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I4be3ac63d466c05eb7a0babb25cb0d41816fbd53

cmd/netlogfmt/main.go

@@ -25,6 +25,7 @@
 package main
 
 import (
+	"cmp"
 	"encoding/base64"
 	"encoding/json"
 	"flag"
@@ -45,7 +46,6 @@ import (
 	"github.com/go-json-experiment/json/jsontext"
 	"tailscale.com/types/logid"
 	"tailscale.com/types/netlogtype"
-	"tailscale.com/util/cmpx"
 	"tailscale.com/util/must"
 )
 
@@ -155,7 +155,7 @@ func printMessage(msg message) {
 		slices.SortFunc(traffic, func(x, y netlogtype.ConnectionCounts) int {
 			nx := x.TxPackets + x.TxBytes + x.RxPackets + x.RxBytes
 			ny := y.TxPackets + y.TxBytes + y.RxPackets + y.RxBytes
-			return cmpx.Compare(ny, nx)
+			return cmp.Compare(ny, nx)
 		})
 		var sum netlogtype.Counts
 		for _, cc := range traffic {