Update version number and HISTORY in main branch (#10694)

Summary:
This PR bumps up version number from 7.7 to 7.8 in main branch, indicating that next release will be 7.8. We are going to release 7.7 soon. Since 7.7.fb branch has been created, we can land this to main.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10694

Reviewed By: gitbw95

Differential Revision: D39581577

Pulled By: riversand963

fbshipit-source-id: 84f3fecf25fd9ac96e46b4cd6d50ddb6edc89427

HISTORY.md

@@ -1,5 +1,7 @@
 # Rocksdb Change Log
 ## Unreleased
+
+## 7.7.0 (09/18/2022)
 ### Bug Fixes
 * Fixed a hang when an operation such as `GetLiveFiles` or `CreateNewBackup` is asked to trigger and wait for memtable flush on a read-only DB. Such indirect requests for memtable flush are now ignored on a read-only DB.
 * Fixed bug where `FlushWAL(true /* sync */)` (used by `GetLiveFilesStorageInfo()`, which is used by checkpoint and backup) could cause parallel writes at the tail of a WAL file to never be synced.

include/rocksdb/version.h

@@ -12,7 +12,7 @@
 // NOTE: in 'main' development branch, this should be the *next*
 // minor or major version number planned for release.
 #define ROCKSDB_MAJOR 7
-#define ROCKSDB_MINOR 7
+#define ROCKSDB_MINOR 8
 #define ROCKSDB_PATCH 0
 
 // Do not use these. We made the mistake of declaring macros starting with