Remove some dead code

drop_in_place has been a lang item, not an intrinsic, for forever

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -852,7 +852,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         }
 
         let instance = match intrinsic {
-            None | Some(ty::IntrinsicDef { name: sym::drop_in_place, .. }) => instance,
+            None => instance,
             Some(intrinsic) => {
                 let mut llargs = Vec::with_capacity(1);
                 let ret_dest = self.make_return_dest(

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -247,7 +247,6 @@ pub fn check_intrinsic_type(
                 ],
                 Ty::new_unit(tcx),
             ),
-            sym::drop_in_place => (1, 0, vec![Ty::new_mut_ptr(tcx, param(0))], Ty::new_unit(tcx)),
             sym::needs_drop => (1, 0, vec![], tcx.types.bool),
 
             sym::type_name => (1, 0, vec![], Ty::new_static_str(tcx)),