Today `-http=:6060` listens on all addresses. Strictly speaking, that is what `:6060` implies, but most users actually only care to access from their own machine. cmd/pprof listens only on localhost when given such an address. Change cmd/trace to match this behavior since it is a safer default and makes cmd/trace more consistent with our other tools. Users that actually want to listen on all addresses can explicitly include the unspecified address (e.g., `-http=0.0.0.0:6060`). For #78921. Change-Id: I47e1fbbdd5374abfeeec10916eb9d2136a6a6964 Reviewed-on: https://go-review.googlesource.com/c/go/+/770461 Reviewed-by: Damien Neil <dneil@google.com> LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Michael Pratt <mpratt@google.com> Reviewed-by: Carlos Amedee <carlos@golang.org>