buildroot

audit: fix build with older kernel versions

This commit adds a patch to audit that fixes the build with kernel
headers newer than 3.13, but older than 3.19. The patch has been
submitted upstream.

Fixes:

  http://autobuild.buildroot.net/results/2d3b2f8c2b9f7f2e04b88b1dccb83e183b5876b6/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>