Update panic machinery to match #[track_caller] changes.

This gets miri's tests passing again with https://github.com/rust-lang/rust/pull/67137.

src/machine.rs

@@ -182,6 +182,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'tcx> {
     #[inline(always)]
     fn find_mir_or_eval_fn(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
+        _span: Span,
         instance: ty::Instance<'tcx>,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,

src/shims/panic.rs

@@ -187,15 +187,12 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 let msg = msg.description();
                 let msg = this.allocate_str(msg, MiriMemoryKind::Env.into());
 
-                // Second arg: Caller location.
-                let location = this.alloc_caller_location_for_span(span);
-
                 // Call the lang item.
                 let panic = this.tcx.lang_items().panic_fn().unwrap();
                 let panic = ty::Instance::mono(this.tcx.tcx, panic);
                 this.call_function(
                     panic,
-                    &[msg.to_ref(), location.ptr.into()],
+                    &[msg.to_ref()],
                     None,
                     StackPopCleanup::Goto { ret: None, unwind },
                 )?;