commit ef3dcd5937c94da5c25df3f3a5d8356d778af8e4
author Dmitri Shuralyov <shurcooL@gmail.com> Tue Mar 28 17:15:02 2017 -0400
committer Brad Fitzpatrick <bradfitz@golang.org> Mon Apr 10 18:12:01 2017 +0000
tree efcba33e04b2ab2bcf3a1731f8e9bd13ef332afe
parent 6e29264c4f0ec543e4fb305d013e2efcf03b71d9

cmd/heapview: look for tools repository in all GOPATH entries

The GOPATH environment variable is defined at
https://golang.org/cmd/go/#hdr-GOPATH_environment_variable as:

> The GOPATH environment variable lists places to look for Go code. On
> Unix, the value is a colon-separated string. On Windows, the value is
> a semicolon-separated string. On Plan 9, the value is a list.

It is legal for Go packages to be in any of those places, not only
the first entry. Look in all places for golang.org/x/tools repository.

Cache the directory that is found. It's slightly more expensive
to look for it, since potentially multiple directories must be
checked for existence.

Updates golang/go#19400.

Change-Id: I16661b7149d52ea6168fffc605c842d7a4da009b
Reviewed-on: https://go-review.googlesource.com/38778
Reviewed-by: Michael Matloob <matloob@golang.org>