Let package_from_installed write the build env into json files in addition to SetEnv.cmd
Let package_from_installed write the build env into json files in addition to SetEnv.cmd

BUG=495204

Review URL: https://codereview.chromium.org/1706423002

git-svn-id: fd409f4bdeea2bb50a5d34bb4d4bfc2046a5a3dd@298862 0039d316-1c4b-4281-b951-d872f2087c98

CoherentLabs/depot_tools,primiano/depot_tools,CoherentLabs/depot_tools,primiano/depot_tools,primiano/depot_tools