Rustdoc doesn't list all cfg's required for an item to be included

In the tokio RuntimeMetrics docs the majority of metrics require --cfg=tokio_unstable. Howver, some also require a target architecture with 64 bit atomics. For metrics which require both of these features rustdoc only shows one of them. Linked is an example: https://docs.rs/tokio/latest/tokio/runtime/struct.RuntimeMetrics.html#method.spawned_tasks_count

Here it says "Available on target_has_atomic="64" only." But it should say something like "Only available with target_has_atomic="64" and tokio_unstable."

Start with the linked RuntimeMetrics documentation entry for spawned_tasks_count and compare its displayed availability conditions with the item's cfg requirements. Trace rustdoc's handling of combined cfg conditions, then verify that items requiring both target_has_atomic="64" and tokio_unstable display both conditions.