Fix a bug in the ptx-kernel calling convention where structs was passed indirectly

Structs being passed indirectly is suprpising and have a high chance not to work as the device and host usually do not share memory.

compiler/rustc_middle/src/ty/layout.rs

@@ -2568,6 +2568,22 @@ where
 
         pointee_info
     }
+
+    fn is_adt(this: TyAndLayout<'tcx>) -> bool {
+        matches!(this.ty.kind(), ty::Adt(..))
+    }
+
+    fn is_never(this: TyAndLayout<'tcx>) -> bool {
+        this.ty.kind() == &ty::Never
+    }
+
+    fn is_tuple(this: TyAndLayout<'tcx>) -> bool {
+        matches!(this.ty.kind(), ty::Tuple(..))
+    }
+
+    fn is_unit(this: TyAndLayout<'tcx>) -> bool {
+        matches!(this.ty.kind(), ty::Tuple(list) if list.len() == 0)
+    }
 }
 
 impl<'tcx> ty::Instance<'tcx> {