all: remove old +build tags

The //go:build syntax was introduced in Go 1.17:

https://go.dev/doc/go1.17#build-lines

gofmt has kept the +build and go:build lines in sync since
then, but enough time has passed. Time to remove them.

Done with:

    perl -i -npe 's,^// \+build.*\n,,' $(git grep -l -F '+build')

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

cmd/containerboot/kube.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build linux
-// +build linux
 
 package main
 

cmd/containerboot/main.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build linux
-// +build linux
 
 // The containerboot binary is a wrapper for starting tailscaled in a
 // container. It handles reading the desired mode of operation out of

cmd/tailscale/cli/diag.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build linux || windows || darwin
-// +build linux windows darwin
 
 package cli
 

cmd/tailscale/cli/diag_other.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !linux && !windows && !darwin
-// +build !linux,!windows,!darwin
 
 package cli
 

cmd/tailscale/cli/ssh_exec.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !js && !windows
-// +build !js,!windows
 
 package cli
 

cmd/tailscale/cli/ssh_unix.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !js && !windows
-// +build !js,!windows
 
 package cli
 

cmd/tailscaled/debug.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.19
-// +build go1.19
 
 package main
 

cmd/tailscaled/install_darwin.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.19
-// +build go1.19
 
 package main
 

cmd/tailscaled/install_windows.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.19
-// +build go1.19
 
 package main
 

cmd/tailscaled/proxy.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.19
-// +build go1.19
 
 // HTTP proxy code
 

cmd/tailscaled/required_version.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !go1.19
-// +build !go1.19
 
 package main
 

cmd/tailscaled/ssh.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build linux || darwin
-// +build linux darwin
 
 package main
 

cmd/tailscaled/tailscaled.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.19
-// +build go1.19
 
 // The tailscaled program is the Tailscale client daemon. It's configured
 // and controlled via the tailscale CLI program.

cmd/tailscaled/tailscaled_bird.go

@@ -3,8 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.19 && (linux || darwin || freebsd || openbsd)
-// +build go1.19
-// +build linux darwin freebsd openbsd
 
 package main
 

cmd/tailscaled/tailscaled_notwindows.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !windows && go1.19
-// +build !windows,go1.19
 
 package main // import "tailscale.com/cmd/tailscaled"
 

cmd/tailscaled/tailscaled_windows.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.19
-// +build go1.19
 
 package main // import "tailscale.com/cmd/tailscaled"
 

cmd/tailscaled/with_cli.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build ts_include_cli
-// +build ts_include_cli
 
 package main
 

cmd/tsshd/tsshd.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build ignore
-// +build ignore
 
 // The tsshd binary was an experimental SSH server that accepts connections
 // from anybody on the same Tailscale network.