* test_eintr: support verbose mode, don't redirect eintr_tester output into
  a pipe
* eintr_tester: replace os.fork() with subprocess to have a cleaner child
  process (ex: don't inherit setitimer())
* eintr_tester: kill the process if the unit test fails
* test_open/test_os_open(): write support.PIPE_MAX_SIZE bytes instead of
  support.PIPE_MAX_SIZE*3 bytes

Skip test_open() and test_os_open(): both tests uses a FIFO and signals, but
there is a bug in the FreeBSD kernel which blocks the test. Skip the tests
until the bug is fixed in FreeBSD kernel.

Remove also debug traces from test_eintr:

* stop using faulthandler to have a timeout
* remove print()

Write also open and close on two lines in test_open() and test_os_open()
tests. If these tests block again, we can know if the test is stuck at open or
close.

test_eintr: don't always run the test in debug mode.

import_init() imports the "_imp" module, not the "imp" module.

format_stack(), and extract_stack() called without arguments.

format_stack(), and extract_stack() called without arguments.

format_stack(), and extract_stack() called without arguments.

Fix test_write(): copy support.PIPE_MAX_SIZE bytes, not support.PIPE_MAX_SIZE*3
bytes.

sys.stderr is sometimes a StringIO. The redirection was just a hack to see
eintr_tester.py output in red in the buildbot output.

ProactorEventLoop now supports SSL.

Some test_eintr hangs on waiting for the child process completion if an error
occurred on the parent. Kill the child process on error (in the parent)
to avoid the hang.

Reported by Jakub Wilk.

Reported by Jakub Wilk.

Reported by Jakub Wilk.

* Add verbose mode to test_eintr
* Always enable verbose mode in test_eintr
* Use faulthandler.dump_traceback_later() with a timeout of 15 minutes in
  eintr_tester.py

Add an unit test on os.waitpid()

Fix the regex to support the version 7.10: minor version with two digits