ANDROID: netfilter: xt_IDLETIMER: Add new netlink msg type

Send notifications when the label becomes active after an idle period.
Send netlink message notifications in addition to sysfs notifications.
Using a uevent with
  subsystem=xt_idletimer
  INTERFACE=...
  STATE={active,inactive}

This is backport from common android-3.0
commit: beb914e987cbbd368988d2b94a6661cb907c4d5a
with uevent support instead of a new netlink message type.

Bug: 120445672
Change-Id: I31677ef00c94b5f82c8457e5bf9e5e584c23c523
Signed-off-by: Ashish Sharma <ashishsharma@google.com>
Signed-off-by: JP Abgrall <jpa@google.com>
[astrachan: Folded the following changes into this patch:
            ee0b238fada5 ("netfilter: xt_IDLETIMER: time-stamp and suspend/resume handling.")
            728c058a495e ("netfilter: xt_IDLETIMER: Adds the uid field in the msg")
            5ebea489d44c ("netfilter: xt_IDLETIMER: Fix use after free condition during work")
            5ab69d7ba2c5 ("netfilter: xt_IDLETIMER: Use fullsock when querying uid")]
Signed-off-by: Alistair Strachan <astrachan@google.com>