Rollup merge of #111587 - cbeuw:copy-for-deref, r=oli-obk

Custom MIR: Support `Rvalue::CopyForDeref`

r? `@oli-obk` or `@tmiasko` or `@JakobDegen`

compiler/rustc_mir_build/src/build/custom/parse/instruction.rs

@@ -154,6 +154,7 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
                 Ok(Rvalue::BinaryOp(BinOp::Offset, Box::new((ptr, offset))))
             },
             @call("mir_len", args) => Ok(Rvalue::Len(self.parse_place(args[0])?)),
+            @call("mir_copy_for_deref", args) => Ok(Rvalue::CopyForDeref(self.parse_place(args[0])?)),
             ExprKind::Borrow { borrow_kind, arg } => Ok(
                 Rvalue::Ref(self.tcx.lifetimes.re_erased, *borrow_kind, self.parse_place(*arg)?)
             ),