Mark some functions not-inline whose definition is out-of-line.

This fixes some instances of -Wundefined-inline in the C++20 build.

Bug: chromium:1284275
Change-Id: I134e866183e1e42b9726153964af9910d03cd3b8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3791525Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Auto-Submit: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82080}

src/heap/marking-visitor.h

@@ -358,7 +358,7 @@ class YoungGenerationMarkingVisitorBase
   }
 
   template <typename TSlot>
-  V8_INLINE void VisitPointerImpl(HeapObject host, TSlot slot);
+  void VisitPointerImpl(HeapObject host, TSlot slot);
 
   MarkingWorklists::Local* worklists_local_;
 };

src/heap/objects-visiting.h

@@ -98,7 +98,7 @@ class HeapVisitor : public ObjectVisitorWithCageBases {
   V8_INLINE ResultType Visit(HeapObject object);
   V8_INLINE ResultType Visit(Map map, HeapObject object);
   // A callback for visiting the map pointer in the object header.
-  V8_INLINE void VisitMapPointer(HeapObject host);
+  void VisitMapPointer(HeapObject host);
 
  protected:
   // A guard predicate for visiting the object.