getCallingSid: get calling security context

This call gets the security context of the calling process when
requested.

Bug: 121035042
Test: boot
Change-Id: Ia8a4c0cb4a9c86dcc0d3b7583014237f879a3074
Merged-In: Ia8a4c0cb4a9c86dcc0d3b7583014237f879a3074
(cherry picked from commit b935356c420bd09b85dcd62fc61baff85b1685ae)
7 files changed