add std.meta.TrailerFlags API

This is useful for saving memory when allocating an object that has many
optional components. The optional objects are allocated sequentially in
memory, and a single integer is used to represent each optional object
and whether it is present based on each corresponding bit.
eac6280241Andrew Kelley committed on 7/15/2020, 12:19:17 AMparenta7c3cec
2 files changedLine totals unavailable