func LabelHandlerFunc(fn func(w http.ResponseWriter, r *http.Request)) http.Handler {
	return &labelHandler{orig: http.HandlerFunc(fn)}
}
LabelHandlerFunc adds "http-path" profiler label to the given handler function.
If you want to start new goroutines from h, propagate the labels by passing r.Context().
package pprofutil
import (
	"context"
	"net/http"
	"runtime/pprof"
)
func LabelHandler(h http.Handler) http.Handler {
	return &labelHandler{orig: h}
}