Move blob_index.h to db/ (#5919)

Summary:
Extracted from PR https://github.com/facebook/rocksdb/issues/5903 for technical reasons.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5919

Test Plan: make check

Differential Revision: D17910132

Pulled By: ltamasi

fbshipit-source-id: 6ecbb8d6e84b2a1d1f28575ad48ac3cc65833eb5

utilities/blob_db/blob_compaction_filter.h

@@ -7,11 +7,11 @@
 
 #include <unordered_set>
 
+#include "db/blob_index.h"
 #include "monitoring/statistics.h"
 #include "rocksdb/compaction_filter.h"
 #include "rocksdb/env.h"
 #include "utilities/blob_db/blob_db_impl.h"
-#include "utilities/blob_db/blob_index.h"
 
 namespace rocksdb {
 namespace blob_db {

utilities/blob_db/blob_db_impl.cc

@@ -11,6 +11,7 @@
 #include <iomanip>
 #include <memory>
 
+#include "db/blob_index.h"
 #include "db/db_impl/db_impl.h"
 #include "db/write_batch_internal.h"
 #include "file/file_util.h"
@@ -40,7 +41,6 @@
 #include "utilities/blob_db/blob_compaction_filter.h"
 #include "utilities/blob_db/blob_db_iterator.h"
 #include "utilities/blob_db/blob_db_listener.h"
-#include "utilities/blob_db/blob_index.h"
 
 namespace {
 int kBlockBasedTableVersionFormat = 2;

utilities/blob_db/blob_db_test.cc

@@ -13,6 +13,7 @@
 #include <string>
 #include <vector>
 
+#include "db/blob_index.h"
 #include "db/db_test_util.h"
 #include "file/file_util.h"
 #include "file/sst_file_manager_impl.h"
@@ -26,7 +27,6 @@
 #include "util/string_util.h"
 #include "utilities/blob_db/blob_db.h"
 #include "utilities/blob_db/blob_db_impl.h"
-#include "utilities/blob_db/blob_index.h"
 
 namespace rocksdb {
 namespace blob_db {