CFI: Fix SIGILL reached via trait objects

Fix #106547 by transforming the concrete self into a reference to a
trait object before emitting type metadata identifiers for trait
methods.

compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs

@@ -207,6 +207,7 @@ fn declare_unused_fn<'tcx>(cx: &CodegenCx<'_, 'tcx>, def_id: DefId) -> Instance<
             )),
             ty::List::empty(),
         ),
+        None,
     );
 
     llvm::set_linkage(llfn, llvm::Linkage::PrivateLinkage);