Rollup merge of #121847 - shamatar:btreemap_fix_implicits, r=cuviper

Remove hidden use of Global

Fixes #121797

library/alloc/src/collections/btree/map.rs

@@ -180,7 +180,7 @@ pub struct BTreeMap<
     /// `ManuallyDrop` to control drop order (needs to be dropped after all the nodes).
     pub(super) alloc: ManuallyDrop<A>,
     // For dropck; the `Box` avoids making the `Unpin` impl more strict than before
-    _marker: PhantomData<crate::boxed::Box<(K, V)>>,
+    _marker: PhantomData<crate::boxed::Box<(K, V), A>>,
 }
 
 #[stable(feature = "btree_drop", since = "1.7.0")]