Auto merge of rust-lang#27555 - dotdash:drop_flag_ty, r=pnkfelix

The drop flags are Lvalue (and thus ByRef) datums that hold a u8 value,
so their value type should be u8, not a pointer to u8.

src/librustc_trans/trans/base.rs

@@ -1299,12 +1299,11 @@ pub fn init_function<'a, 'tcx>(fcx: &'a FunctionContext<'a, 'tcx>,
  let init_val = C_u8(fcx.ccx, adt::DTOR_NEEDED_HINT);
  let llname = &format!("dropflag_hint_{}", id);
  debug!("adding hint {}", llname);
- let ptr = alloc_ty(entry_bcx, tcx.types.u8, llname);
+ let ty = tcx.types.u8;
+ let ptr = alloc_ty(entry_bcx, ty, llname);
  Store(entry_bcx, init_val, ptr);
- let ty = tcx.mk_ptr(ty::TypeAndMut { ty: tcx.types.u8, mutbl: ast::MutMutable });
  let flag = datum::Lvalue::new_dropflag_hint("base::init_function");
- let datum = datum::Datum::new(ptr, ty, flag);
- datum
+ datum::Datum::new(ptr, ty, flag)
  };
 
  let (var, datum) = match info {