Allow missing OpenVPN pid file on shutdown

If the OpenVPN process has already exited, the pid file will
have been removed.  Allow this to fail silently.

BUG=chromium:377962
TEST=Run this test

Change-Id: I1fff3b7a17a862c88c60abea7c5a52a8d57e091b
Reviewed-on: https://chromium-review.googlesource.com/201669
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Commit-Queue: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
1 file changed