Do not allow priv_apps to scan all exec files

Bug: 36463595
Test: sailfish boots without new denials

Change-Id: I4271a293b91ab262dddd4d40220cd7daaff53bf2
Signed-off-by: Sandeep Patil <sspatil@google.com>
(cherry picked from commit b2586825e1ce92d637754b4c40e4d5edfd50a1a6)