SDK-2036. MegaApi::getFavorites() returns non-favorite nodes.
SDK-2036. MegaApi::getFavorites() returns non-favorite nodes.

Avoid FavouriteProcessor::processNode() to take into account empty/zero
values for 'fav' node attribute.

Note: they shouldn't even exist, as they should be deleted when this
attribute is set to zero.

meganz/sdk,meganz/sdk,meganz/sdk,meganz/sdk,meganz/sdk,meganz/sdk,meganz/sdk