Codemod NULL to nullptr

Summary:
scripted NULL to nullptr in
* include/leveldb/
* db/
* table/
* util/

Test Plan: make all check

Reviewers: dhruba, emayanke

Reviewed By: emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9003

db/table_cache.h

@@ -25,15 +25,15 @@ class TableCache {
 
   // Return an iterator for the specified file number (the corresponding
   // file length must be exactly "file_size" bytes).  If "tableptr" is
-  // non-NULL, also sets "*tableptr" to point to the Table object
-  // underlying the returned iterator, or NULL if no Table object underlies
+  // non-nullptr, also sets "*tableptr" to point to the Table object
+  // underlying the returned iterator, or nullptr if no Table object underlies
   // the returned iterator.  The returned "*tableptr" object is owned by
   // the cache and should not be deleted, and is valid for as long as the
   // returned iterator is live.
   Iterator* NewIterator(const ReadOptions& options,
                         uint64_t file_number,
                         uint64_t file_size,
-                        Table** tableptr = NULL);
+                        Table** tableptr = nullptr);
 
   // If a seek to internal key "k" in specified file finds an entry,
   // call (*handle_result)(arg, found_key, found_value).
@@ -55,7 +55,7 @@ class TableCache {
   std::shared_ptr<Cache> cache_;
 
   Status FindTable(uint64_t file_number, uint64_t file_size, Cache::Handle**,
-                   bool* tableIO = NULL);
+                   bool* tableIO = nullptr);
 };
 
 }  // namespace leveldb