If we create separate listening sockets in each worker using
SO_REUSEADDR, then an incoming connection may be load-balanced
to a process that is already busy, either due to a long-running
request, or because it is a recursive request (in which case we
would deadlock).

Instead, only create one listening socket, and only create worker
forks afterwards. This way the incoming request will be served
by one of the workers that is currently listening for an incoming
connection.

* PHP-7.4:
  Update year to 2021

Closes GH-6636.

CentOS 7 ships with re2c 0.13.5 by default, so we should not have
bumped the required re2c version to 0.13.7.  However, 0.13.5 does not
support default rules, so we cannot use them to fix bug 76813.

This reverts commit 420184ad529443182c9a348a55b1c9216005c613 and
5e15c9c41f8318a8392c2e2c78544f218736549c.

Closes GH-6593.

This reverts commit 5e15c9c41f8318a8392c2e2c78544f218736549c, since
re2c default rules are only available as of re2c 0.13.7.

phpdbg now disables JIT, so these cause XFAIL warnings.

These are useful to seed typed property fuzzing.

* PHP-7.4:
  Fix #76813: Access violation near NULL on source operand