Useful for potentially huge bitsets that are expected to be mostly
filled with zeroes, reducing memory consumption by assuming bits being
zero by default (without wasting memory to store zeroes).
Co-authored-by: Alyssa Rosenzweig <alyssa.rosenzweig@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37908>
