Fixed the shadowing in db/compaction.cc and include/rocksdb/db.h

Summary:
Fixed the shadowing in db/compaction.cc and include/rocksdb/db.h

Test Plan:
make

db/compaction.cc

@@ -79,22 +79,22 @@ Compaction::Compaction(int number_levels, int start_level, int out_level,
 }
 
 Compaction::Compaction(VersionStorageInfo* vstorage,
-    const autovector<CompactionInputFiles>& inputs,
-    int start_level, int output_level,
-    uint64_t max_grandparent_overlap_bytes,
-    const CompactionOptions& options,
-    bool deletion_compaction)
-    : start_level_(start_level),
-      output_level_(output_level),
-      max_output_file_size_(options.output_file_size_limit),
-      max_grandparent_overlap_bytes_(max_grandparent_overlap_bytes),
-      input_version_(nullptr),  // TODO(yhchiang): set it later
+    const autovector<CompactionInputFiles>& _inputs,
+    int _start_level, int _output_level,
+    uint64_t _max_grandparent_overlap_bytes,
+    const CompactionOptions& _options,
+    bool _deletion_compaction)
+    : start_level_(_start_level),
+      output_level_(_output_level),
+      max_output_file_size_(_options.output_file_size_limit),
+      max_grandparent_overlap_bytes_(_max_grandparent_overlap_bytes),
+      input_version_(nullptr),
       number_levels_(vstorage->num_levels()),
       cfd_(nullptr),
-      output_compression_(options.compression),
+      output_compression_(_options.compression),
       seek_compaction_(false),
-      deletion_compaction_(deletion_compaction),
-      inputs_(inputs),
+      deletion_compaction_(_deletion_compaction),
+      inputs_(_inputs),
       grandparent_index_(0),
       seen_key_(false),
       overlapped_bytes_(0),

include/rocksdb/db.h

@@ -501,7 +501,7 @@ class DB {
       ColumnFamilyMetaData* metadata) {}
 
   // Get the metadata of the default column family.
-  virtual void GetColumnFamilyMetaData(
+  void GetColumnFamilyMetaData(
       ColumnFamilyMetaData* metadata) {
     GetColumnFamilyMetaData(DefaultColumnFamily(), metadata);
   }