v.io/x/devtools: make sure GOARCH, GOOS, GOPATH are written to profiles.
v.io/x/devtools: make sure GOARCH, GOOS, GOPATH are written to profiles.

Change-Id: I1e63ce8a20c4e0fc8bab727329969f89f0a53334

vanadium/go.devtools,vanadium/go.devtools,vanadium/go.devtools