runtime: document that tracefpunwindoff applies to some profilers
The tracefpunwindoff GODEBUG applies to all the places where we use
frame pointer unwinding. Originally that was just the execution tracer,
but now we also use it for the block and mutex profilers.
Change-Id: I6a6a69641fede668d96335582dba6d43e62f6a51
Reviewed-on: https://go-review.googlesource.com/c/go/+/718522
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Nick Ripley <nick.ripley@datadoghq.com> Reviewed-by: Michael Pratt <mpratt@google.com>