Add screencap domain.

Only seeing this denial in permissive:
allow shell screencap_exec:file getattr;

Bug: 37565047
Test: adb shell screencap w/o root
Test: cts-tradefed run cts-dev --module CtsAadbHostTestCases
Merged-In: I9f31d2067e002e7042646ee38dbfc06687481ac7
Change-Id: I9f31d2067e002e7042646ee38dbfc06687481ac7
8 files changed