Reserve AID_AUDIT

AID_AUDIT will be used for an audit daemon for gathering
and controlling the Linux audit subsystem.

Change-Id: I95d597524b5547a60f3a59f692b4b0a6df0a9645

Conflicts:

	include/private/android_filesystem_config.h

Conflicts:
	include/private/android_filesystem_config.h
Auditd initial commit

Initial commit for an audit daemon that
writes kernel audit messages to a log
file. The daemon runs in uid "audit" or
AID_AUDIT.

The log files are located at /data/misc/audit/
The daemon maintains two files at this location:
audit.log and optionally audit.old. On boot (
if the file is non-zero in size), or
when a fixed threshold is hit, the daemon rotates
audit.log to audit.old.

Optionally, if passed the -k option, the daemon polls
dmesg for all lines that contain "audit" and writes
them into the log. After that it continues to operate
as normal, receiving the messages from the netlink
socket.

Change-Id: I5b5037a5a8b39a054213848249afb7808f8b0ffa
Sync with master auditd.
sys/capability.h does not exist in the 4.2 bionic.
auditd: Fix includes for capset