commit b258a532fdb86d080b7cf3d08709283cd1d8bf16
author Todd Wang <toddw@google.com> Thu May 14 22:01:09 2015 -0700
committer Todd Wang <toddw@google.com> Thu May 14 22:01:13 2015 -0700
tree 095a1602ca50c8f9500bca3ec83b3112d5779427
parent b9865831037c2bc74d4ea6622f8052ab3a815296

lib: Replace x/devtools/internal/envutil with x/lib/envvar

A while ago I wrote envutil in the devtools repo, to make it
easier to deal with environment variables, and to make it easy
for the v23 tool to keep track of the mutations it had made.

Later on I noticed that there was similar code in x/ref in a few
places.

This CL removes envutil, and adds a new package envvar that may
be used by all other packages.  It behaves similarly to envutil,
and also to the code scattered around x/ref.

In a subsequent CL I'll add cmdline support for environment
variables using envvar.

MultiPart: 1/2

Change-Id: Idf25fc4e4d1a6ac673bb4ec78fb76e07ee0cebd2