genfs_contexts

Since kernel 4.1 ftrace is supported as a new separate filesystem. It
gets automatically mounted by the kernel under the old path
/sys/kernel/debug/tracing. Because it lives now on a separate device
some sepolicy rules need to be updated. This patch is doing that. Most
of the rules are created based on a conversation happened on the SELinux
Android mailing list:

http://comments.gmane.org/gmane.comp.security.seandroid/2799



Note, that this also needs 3a343a1 from the 4.4 branch in kernel/common.
Also note that when tracefs is auto mounted by the kernel, the kernel
does not use the "mode" parameter specified to mount debugfs for
tracefs. So an extra line like

   chmod 0755 /sys/kernel/debug/tracing

is necessary in init.${ro.hardware}.rc after debugfs was mounted.

Signed-off-by: Christian Poetzsch <christian.potzsch@imgtec.com>

(cherry picked from commit 4dafa72a)

Change-Id: I75738c756b49da4ac109ae442ee37c1e2844ff0a