Rollup merge of #107163 - mikebenfield:parameters-pr, r=TaKO8Ki

Remove some superfluous type parameters from layout.rs.

Specifically remove V, which can always be VariantIdx, and F, which can always be Layout.

compiler/rustc_middle/src/arena.rs

@@ -8,7 +8,7 @@
 macro_rules! arena_types {
     ($macro:path) => (
         $macro!([
-            [] layout: rustc_target::abi::LayoutS<rustc_target::abi::VariantIdx>,
+            [] layout: rustc_target::abi::LayoutS,
             [] fn_abi: rustc_target::abi::call::FnAbi<'tcx, rustc_middle::ty::Ty<'tcx>>,
             // AdtDef are interned and compared by address
             [decode] adt_def: rustc_middle::ty::AdtDefData,