Use copy2 when making readable copies of files
Use copy2 when making readable copies of files

This will gives the copies the same last access and last modification
time as the original file, which is desirable when using isolate with
android (since they want to tell if a file is new based on the time
stamp).

BUG=

Review URL: https://chromiumcodereview.appspot.com/18694003

git-svn-id: d5a9b8648c52d490875de6588c8ee7ca688f9ed1@210315 0039d316-1c4b-4281-b951-d872f2087c98

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py