Move mGlobalGids and mSystemPermissions

This is the last tiny move before moving methods to grant/update
permissions.

Bug: 63539144
Test: Manual. Builds and runs
Test: cts-tradefed run commandAndExit cts-dev -m CtsAppSecurityHostTestCases -t android.appsecurity.cts.PermissionsHostTest
Test: cts-tradefed run commandAndExit cts-dev -m CtsPermissionTestCases
Test: cts-tradefed run commandAndExit cts-dev -m CtsPermission2TestCases
Test: bit FrameworksServicesTests:com.android.server.pm.PackageManagerSettingsTests
Change-Id: Ic2138cf1e442d9d10e8a3ad6dfa24c403aaeca67