wasm: drop pprof dependency

We can use the browser tools to profile, pprof adds 200K to the binary size.

Updates #3157

Signed-off-by: Mihai Parparita <mihai@tailscale.com>

wgengine/watchdog.go

@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !js
+// +build !js
+
 package wgengine
 
 import (