CHROMIUM: relabel some fs at init start.

devtmpfs is created by kernel before SELinux loads. Kernel has no
context about SELinux, thus /dev is having wrong file contexts for
individually labelled file.

init should re-label existing file in /dev to make sure it has the right
contexts.

Currently, NYC didn't combine with CrOS policies, so re-labeling it will
lead to EPERM. We silently ignore the errors occurred during restorecon
for now. This should be fixed once everything has CrOS policies
combined.

BUG=b:69139821
TEST=build_images with kevin and kevin-arcnext

Reviewed-on: https://chromium-review.googlesource.com/1140022
Change-Id: I0351579ec83260022c252aebb7c7d411990c6fb3
2 files changed