Retire SecurityManager.

This change removes all the code that was calling getSecurityManager, and
removes all use of AccessController.doPrivileged. It also changes the
implementation of AccessController so it doesn't actually do anything; it's
only there for source-level compatibility.

Bug: 2585285
Change-Id: I1f0295a4f12bce0316d8073011d8593fee116f71
126 files changed