Convert delayed_bugs to bugs.

I have a suspicion that quite a few delayed bug paths are impossible to
reach, so I did an experiment.

I converted every `delayed_bug` to a `bug`, ran the full test suite,
then converted back every `bug` that was hit. A surprising number were
never hit.

The next commit will convert some more back, based on human judgment.

compiler/rustc_ty_utils/src/layout.rs

@@ -90,8 +90,7 @@ fn univariant_uninterned<'tcx>(
     let dl = cx.data_layout();
     let pack = repr.pack;
     if pack.is_some() && repr.align.is_some() {
-        cx.tcx.dcx().delayed_bug("struct cannot be packed and aligned");
-        return Err(cx.tcx.arena.alloc(LayoutError::Unknown(ty)));
+        cx.tcx.dcx().bug("struct cannot be packed and aligned");
     }
 
     cx.univariant(dl, fields, repr, kind).ok_or_else(|| error(cx, LayoutError::SizeOverflow(ty)))