Remove 'virtual' when implied by 'override' (#12319)

Summary:
... to follow modern C++ style / idioms.

Used this hack:
```
for FILE in `cat my_list_of_files`; do perl -pi -e 'BEGIN{undef $/;} s/ virtual( [^;{]* override)/$1/smg' $FILE; done
```

Pull Request resolved: https://github.com/facebook/rocksdb/pull/12319

Test Plan: existing tests, CI

Reviewed By: jaykorean

Differential Revision: D53275303

Pulled By: pdillinger

fbshipit-source-id: bc0881af270aa8ef4d0ae4f44c5a6614b6407377

2 files changed, 12 insertions, 10 deletions

diff --git a/memtable/hash_linklist_rep.cc b/memtable/hash_linklist_rep.cc
index a75587917..7a87c7ed5 100644
--- a/memtable/hash_linklist_rep.cc
+++ b/memtable/hash_linklist_rep.cc
@@ -887,14 +887,15 @@ class HashLinkListRepFactory : public MemTableRepFactory {
   }
 
   using MemTableRepFactory::CreateMemTableRep;
-  virtual MemTableRep* CreateMemTableRep(
-      const MemTableRep::KeyComparator& compare, Allocator* allocator,
-      const SliceTransform* transform, Logger* logger) override;
+  MemTableRep* CreateMemTableRep(const MemTableRep::KeyComparator& compare,
+                                 Allocator* allocator,
+                                 const SliceTransform* transform,
+                                 Logger* logger) override;
 
   static const char* kClassName() { return "HashLinkListRepFactory"; }
   static const char* kNickName() { return "hash_linkedlist"; }
-  virtual const char* Name() const override { return kClassName(); }
-  virtual const char* NickName() const override { return kNickName(); }
+  const char* Name() const override { return kClassName(); }
+  const char* NickName() const override { return kNickName(); }
 
  private:
   HashLinkListRepOptions options_;
diff --git a/memtable/hash_skiplist_rep.cc b/memtable/hash_skiplist_rep.cc
index aed1580c4..ca4c376db 100644
--- a/memtable/hash_skiplist_rep.cc
+++ b/memtable/hash_skiplist_rep.cc
@@ -357,15 +357,16 @@ class HashSkipListRepFactory : public MemTableRepFactory {
   }
 
   using MemTableRepFactory::CreateMemTableRep;
-  virtual MemTableRep* CreateMemTableRep(
-      const MemTableRep::KeyComparator& compare, Allocator* allocator,
-      const SliceTransform* transform, Logger* logger) override;
+  MemTableRep* CreateMemTableRep(const MemTableRep::KeyComparator& compare,
+                                 Allocator* allocator,
+                                 const SliceTransform* transform,
+                                 Logger* logger) override;
 
   static const char* kClassName() { return "HashSkipListRepFactory"; }
   static const char* kNickName() { return "prefix_hash"; }
 
-  virtual const char* Name() const override { return kClassName(); }
-  virtual const char* NickName() const override { return kNickName(); }
+  const char* Name() const override { return kClassName(); }
+  const char* NickName() const override { return kNickName(); }
 
  private:
   HashSkipListRepOptions options_;