util/deephash: move internal/deephash to util/deephash

No code changes. Just a minor package doc addition about lack of API
stability.

cmd/tailscaled/depaware.txt

@@ -84,7 +84,6 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/disco                                          from tailscale.com/derp+
         tailscale.com/health                                         from tailscale.com/control/controlclient+
         tailscale.com/hostinfo                                       from tailscale.com/control/controlclient+
-        tailscale.com/internal/deephash                              from tailscale.com/ipn/ipnlocal+
         tailscale.com/ipn                                            from tailscale.com/ipn/ipnserver+
         tailscale.com/ipn/ipnlocal                                   from tailscale.com/ipn/ipnserver+
         tailscale.com/ipn/ipnserver                                  from tailscale.com/cmd/tailscaled
@@ -137,6 +136,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/types/structs                                  from tailscale.com/control/controlclient+
         tailscale.com/types/wgkey                                    from tailscale.com/control/controlclient+
    L    tailscale.com/util/cmpver                                    from tailscale.com/net/dns
+        tailscale.com/util/deephash                                  from tailscale.com/ipn/ipnlocal+
         tailscale.com/util/dnsname                                   from tailscale.com/ipn/ipnstate+
   LW    tailscale.com/util/endian                                    from tailscale.com/net/netns+
         tailscale.com/util/groupmember                               from tailscale.com/ipn/ipnserver

ipn/ipnlocal/local.go

@@ -29,7 +29,6 @@ import (
 	"tailscale.com/client/tailscale/apitype"
 	"tailscale.com/control/controlclient"
 	"tailscale.com/health"
-	"tailscale.com/internal/deephash"
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/ipn/policy"
@@ -46,6 +45,7 @@ import (
 	"tailscale.com/types/persist"
 	"tailscale.com/types/preftype"
 	"tailscale.com/types/wgkey"
+	"tailscale.com/util/deephash"
 	"tailscale.com/util/dnsname"
 	"tailscale.com/util/osshare"
 	"tailscale.com/util/systemd"

internal/deephash/deephash.go → util/deephash/deephash.go

@@ -4,6 +4,9 @@
 
 // Package deephash hashes a Go value recursively, in a predictable
 // order, without looping.
+//
+// This package, like most of the tailscale.com Go module, should be
+// considered Tailscale-internal; we make no API promises.
 package deephash
 
 import (

wgengine/userspace.go

@@ -26,7 +26,6 @@ import (
 	"inet.af/netaddr"
 	"tailscale.com/control/controlclient"
 	"tailscale.com/health"
-	"tailscale.com/internal/deephash"
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/net/dns"
 	"tailscale.com/net/dns/resolver"
@@ -42,6 +41,7 @@ import (
 	"tailscale.com/types/logger"
 	"tailscale.com/types/netmap"
 	"tailscale.com/types/wgkey"
+	"tailscale.com/util/deephash"
 	"tailscale.com/version"
 	"tailscale.com/wgengine/filter"
 	"tailscale.com/wgengine/magicsock"