Fix and re-enable mini-core test

Author: antoyo

example/mini_core.rs

@@ -671,7 +671,7 @@ pub mod intrinsics {
     #[rustc_intrinsic]
     pub unsafe fn ctlz_nonzero<T>(x: T) -> u32;
     #[rustc_intrinsic]
-    pub fn needs_drop<T: ?::Sized>() -> bool;
+    pub const fn needs_drop<T: ?::Sized>() -> bool;
     #[rustc_intrinsic]
     pub fn bitreverse<T>(x: T) -> T;
     #[rustc_intrinsic]

example/mini_core_hello_world.rs

@@ -198,8 +198,6 @@ fn main() {
         assert_eq!(intrinsics::align_of::<u16>() as u8, 2);
         assert_eq!(intrinsics::align_of_val(&a) as u8, intrinsics::align_of::<&str>() as u8);
 
-        /*
-         * TODO: re-enable in the next sync.
         let u8_needs_drop = const { intrinsics::needs_drop::<u8>() };
         assert!(!u8_needs_drop);
         let slice_needs_drop = const { intrinsics::needs_drop::<[u8]>() };
@@ -208,7 +206,6 @@ fn main() {
         assert!(noisy_drop);
         let noisy_unsized_drop = const { intrinsics::needs_drop::<NoisyDropUnsized>() };
         assert!(noisy_unsized_drop);
-        */
 
         Unique {
             pointer: 0 as *const &str,