Fix fault handler to unregister on shutdown

This fixes a problem with the fault handler where it wasn't
unregistering itself during shutdown of the runtime.

Bug: 17133266

(cherry picked from commit e8b9afcd0cd86b8808af29a97332038aab70c604)

Change-Id: I1a4ec4292ec049046dda30769265680201729efb
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index ba53c43..ee8cbe1 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -169,6 +169,9 @@
     BackgroundMethodSamplingProfiler::Shutdown();
   }
 
+  // Shutdown the fault manager if it was initialized.
+  fault_manager.Shutdown();
+
   Trace::Shutdown();
 
   // Make sure to let the GC complete if it is running.