We already patch ZEO4 with TCP_NODELAY patch (see 5cf4cf1f "ERP5:
enable TCP_NODELAY for ZEO") and we will need to backport more patches
to ZEO4 branch for wendelin.core 2 to work correctly.

It's not only software/neoppod which uses ZEO, and it is not convenient for
all other software-releases to inherit from neoppod to use correct
version and build of ZEO egg. For this reason factor out details of ZEO
egg building into component/ZEO and let users use ${ZEO:egg} where ZEO
is needed. This way ZEO will be correctly installed for all users.

This patch should be a non-functional change. We switch to
ZEO@5114f909 revision which corresponds to ZEO 4.3.1 +
TCP_NODELAY.patch

Adding other patches to ZEO4 needed by wendelin.core 2 will be done as a
separate step.

This reverts commit 1c2d1c0a.
because NEO is not ready for such change.

They say that `zodbpickle.binary` is now much more lightweight on CPython2:
https://github.com/zopefoundation/zodbpickle/blob/master/CHANGES.rst#200-2019-11-13

For some SR, it implies the following upgrades:
- decorator: 4.3.0
- gitdb2: 2.0.5
- smmap2: 2.0.5
- subprocess32: 3.5.3

Since 10.4, it seems mysql_install_db does not take anymore
BASEDIR/lib/plugin as default value for plugin_dir.