Smack: Ptrace access check mode

Smack: Ptrace access check mode

When the ptrace security hooks were split the addition of
a mode parameter was not taken advantage of in the Smack
ptrace access check. This changes the access check from
always looking for read and write access to using the
passed mode. This will make use of /proc much happier.

Targeted for git://git.gitorious.org/smack-next/kernel.git

Change-Id: I979f36da1b26d0fba5d73744f340422aaae5cc74
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>