netfilter: qtaguid: initialize a local var to keep compiler happy.

There was a case that might have seemed like new_tag_stat was not
initialized and actually used.
Added comment explaining why it was impossible, and a BUG()
in case the logic gets changed.

Change-Id: I1eddd1b6f754c08a3bf89f7e9427e5dce1dfb081
Signed-off-by: JP Abgrall <jpa@google.com>
netfilter: xt_qtaguid: update to msm-3.4

AU_LINUX_ANDROID_JB_MR2.04.03.00.110.011

Change-Id: I8912242c95270f21b0d21dc859c56f0d0342d8c0
defconfig: Update netfilter options