Auto merge of #139992 - matthiaskrgr:rollup-ak3uibu, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - #139351 (Autodiff batching2)
 - #139483 (f*::NAN: guarantee that this is a quiet NaN)
 - #139498 (Ignore zero-sized types in wasm future-compat warning)
 - #139967 (Introduce and use specialized `//@ ignore-auxiliary` for test support files instead of using `//@ ignore-test`)
 - #139969 (update libc)
 - #139971 (Make C string merging test work on MIPS)
 - #139974 (Change `InterpCx::instantiate*` function visibility to pub)
 - #139977 (Fix drop handling in `hint::select_unpredictable`)

r? `@ghost`
`@rustbot` modify labels: rollup