Previously, gears.object.properties used a weak table for adding
additional information to a C object. However, weak tables can easily
cause leaks when the value references the key.
This commit makes the code instead use the new .data property that is
available on all C objects. This means we have no more magic with a weak
table and instead only use "regular" tables instead.
Signed-off-by: Uli Schlachter <psychon@znc.in>
b6a3ae43fb