This should address the following:

• Tests that rely on blockBatonASIOBeforePoll should query FailPointEnableBlock ::initialTimesEntered() before blocking on the fail-point.
• The main test thread should ensure the fail-point is enabled before running any blocking code that would trigger poll().

This should ensure the following sequence:
The fail-point is enabled.
The main thread then enters blocking code, internally running poll().
The thread setting the fail-point can then use FailPoint::waitForTimesEntered() to wait for the main test thread to block on the fail-point.