cmd: update vendored pprof

cmd: update vendored pprof

  go get github.com/google/pprof@latest
  go mod vendor

Plus a tiny change to the pprof command to match an upstream interface
change.

Updates #36905.

Change-Id: I4c7bbe8c317a6eeb217fce971b208f96ab0727fa
Reviewed-on: https://go-review.googlesource.com/c/go/+/393370
Trust: Heschi Kreinick <heschi@google.com>
Run-TryBot: Heschi Kreinick <heschi@google.com>
Auto-Submit: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>