Use consisntent style of size_of in query type erasure

All other impls replace type generics with `()` (or a type implementing the necessery traits)
and lifetimes with `'static`, do the same for those impls.

compiler/rustc_middle/src/query/erase.rs

@@ -46,15 +46,15 @@ pub fn restore<T: EraseType>(value: Erase<T>) -> T {
 }
 
 impl<T> EraseType for &'_ T {
-    type Result = [u8; size_of::<*const ()>()];
+    type Result = [u8; size_of::<&'static ()>()];
 }
 
 impl<T> EraseType for &'_ [T] {
-    type Result = [u8; size_of::<*const [()]>()];
+    type Result = [u8; size_of::<&'static [()]>()];
 }
 
 impl<T> EraseType for &'_ ty::List<T> {
-    type Result = [u8; size_of::<*const ()>()];
+    type Result = [u8; size_of::<&'static ty::List<()>>()];
 }
 
 impl<I: rustc_index::Idx, T> EraseType for &'_ rustc_index::IndexSlice<I, T> {