s4:libnet:py_net - free event context in dealloc fn

s4:libnet:py_net - free event context in dealloc fn

Creation of a new Net() object initializes an event context under
a NULL talloc context and then creates a new talloc context as a
child of the event context. The deallocation function for the
net object only frees the child and not the parent. This leaks an
fd for the tevent context and associated memory.

Signed-off-by: Andrew Walker <awalker@ixsystems.com>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Fri Nov  6 04:58:31 UTC 2020 on sn-devel-184