Revert^3 "Add spin loop to mutex, overhaul monitor""

This reverts commit 3d52abe40e619497b1b59cfce92c74b5a417add5.

Reason for revert: Causes asan build timeout; Apparently the runtime
goes away while we're holding a system mutex. We now sleep forever
without releasing it.

Bug: 140590186
Bug: 121302864
Change-Id: I9e4dcaf820815c751aa803473809955451988ebd
17 files changed