Allow callers of uevent_kernel_*() access to /proc/sys/kernel/overflowuid

Bug: 62378620
Test: Android in Chrome OS can call uevent_kernel_recv() and not fail
      with EIO.
Test: bullhead networking still works

Change-Id: I4dd5d2148ee1704c4fa23d7fd82d1ade19b58cbd
9 files changed