Issue #22685: Fix test_pause_reading() of test_subprocess
Issue #22685: Fix test_pause_reading() of test_subprocess

Override the connect_read_pipe() method of the loop to mock immediatly
pause_reading() and resume_reading() methods.

The test failed randomly on FreeBSD 9 buildbot and on Windows using trollius.

overcastcloud/trollius,overcastcloud/trollius,overcastcloud/trollius