Update master to version 6.13 (#7378)

Summary:
for release fork

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7378

Test Plan: make check + CI

Reviewed By: jay-zhuang

Differential Revision: D23669163

Pulled By: pdillinger

fbshipit-source-id: 14cbf95b32717c28418c71cc8e10f06733bbc49f

HISTORY.md

 # Rocksdb Change Log
-## Unreleased
+## 6.13 (09/12/2020)
 ### Bug fixes
 * Fix a performance regression introduced in 6.4 that makes a upper bound check for every Next() even if keys are within a data block that is within the upper bound.
 * Fix a possible corruption to the LSM state (overlapping files within a level) when a `CompactRange()` for refitting levels (`CompactRangeOptions::change_level == true`) and another manual compaction are executed in parallel.

include/rocksdb/version.h

@@ -5,7 +5,7 @@
 #pragma once
 
 #define ROCKSDB_MAJOR 6
-#define ROCKSDB_MINOR 12
+#define ROCKSDB_MINOR 13
 #define ROCKSDB_PATCH 0
 
 // Do not use these. We made the mistake of declaring macros starting with