Rollup merge of #70808 - hermitcore:tls, r=dtolnay

Simplify dtor registration for HermitCore by using a list of destructors

The implementation is similar to the macOS version and doesn't depend on additional OS support

diff --cc src/libstd/sys/hermit/thread.rs
index 0bb774ca137ee2fe82189c366af94d20e65cf8b3,c0ee2829f09afc50bc3985b478b669adcee77233..7e3fb4c6d20523ebd9430a33064d936c5a28cccb
--- 1/src/libstd/sys/hermit/thread.rs
--- 2/src/libstd/sys/hermit/thread.rs
+++ b/src/libstd/sys/hermit/thread.rs
@@@ -4,7 -4,10 +4,8 @@@ use crate::ffi::CStr
  use crate::io;
  use crate::mem;
  use crate::sys::hermit::abi;
+ use crate::sys::hermit::fast_thread_local::run_dtors;
  use crate::time::Duration;
 -use core::u32;
  
  pub type Tid = abi::Tid;