ICE on invalid thread ID in Linux pthread_getname_np

[RalfJung]

This program ICEs Miri:

fn get_thread_name(name: &mut [u8]) -> i32 { unsafe {
    libc::pthread_getname_np(999, name.as_mut_ptr().cast(), name.len())
} }

fn main() {
     get_thread_name(&mut []);
}

Thanks to @YohDeadfall for mentioning that. This is definitely a bug, we should never ICE.

[YohDeadfall]

@rustbot claim