SurfaceFlinger: Reset VsyncReactor's timer thread

If any of the syscalls the timer uses returns an error, reset the timer.
This is a workaround for an issue seen where VsyncReactor is not calling
new callbacks. In addition this change adds more log prints to help
identifying the underlying issue.

Bug: 151892277
Test: simulate an error in syscall and observe timer resets
Change-Id: I6fd62f9d73f75f32a87d1483cea14f3f1b358507
diff --git a/services/surfaceflinger/Scheduler/TimeKeeper.h b/services/surfaceflinger/Scheduler/TimeKeeper.h
index 38f0708..da2195c 100644
--- a/services/surfaceflinger/Scheduler/TimeKeeper.h
+++ b/services/surfaceflinger/Scheduler/TimeKeeper.h
@@ -53,6 +53,8 @@
      */
     virtual void alarmCancel() = 0;
 
+    virtual void dump(std::string& result) const = 0;
+
 protected:
     TimeKeeper(TimeKeeper const&) = delete;
     TimeKeeper& operator=(TimeKeeper const&) = delete;