Rollup merge of #105998 - RalfJung:no-unwind-panic-msg, r=thomcc

adjust message on non-unwinding panic

"thread panicked while panicking" is just plain wrong in case this is a non-unwinding panic, such as
- a panic out of a `nounwind` function
- the sanity checks we have in `mem::uninitialized` and `mem::zeroed`
- the optional debug assertion in various unsafe std library functions

library/std/src/panicking.rs

@@ -699,7 +699,11 @@ fn rust_panic_with_hook(
         // have limited options. Currently our preference is to
         // just abort. In the future we may consider resuming
         // unwinding or otherwise exiting the thread cleanly.
-        rtprintpanic!("thread panicked while panicking. aborting.\n");
+        if !can_unwind {
+            rtprintpanic!("thread caused non-unwinding panic. aborting.\n");
+        } else {
+            rtprintpanic!("thread panicked while panicking. aborting.\n");
+        }
         crate::sys::abort_internal();
     }