misc/pprof: fix address lookup regression on Linux
misc/pprof: fix address lookup regression on Linux

Just use "go tool addr2line" no matter what, since we know
it works for all OSs.

Fixes issue 4818.

R=rsc, r
CC=golang-dev
https://codereview.appspot.com/7526047

Committer: Rob Pike <4dc7c9ec434ed06502767136789763ec11d2c4b7@golang.org>
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go