[selinux] allow system_server to call INCFS_IOC_GET_FILLED_BLOCKS ioctl

This allows Incremental Service (part of system_server) to query the
filled blocks of files on Incremental File System.

Test: atest service.incremental_test
BUG: 165799231
Change-Id: Id63f8f325d92fef978a1ad75bd6eaa8aa5e9e68b
4 files changed