[RocksDB] Fix a race condition in GetSortedWalFiles

Summary: This patch fixed a race condition where a log file is moved to archived dir in the middle of GetSortedWalFiles. Without the fix, the log file would be missed in the result, which leads to transaction log iterator gap. A test utility SyncPoint is added to help reproducing the race condition.

Test Plan: TransactionLogIteratorRace; make check

Reviewers: dhruba, ljin

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17121
[C-API] added "rocksdb_options_set_plain_table_factory" to make it possible to use plain table factory
[C-API] implemented more options
Add script auto_sanity_test.sh to perform auto sanity test

Summary:
Add script auto_sanity_test.sh to perform auto sanity test

usage: auto_sanity_test.sh [new_commit] [old_commit]

Running without commit parameter will do the sanity test with the latest
and the latest 10 commit.

Test Plan: ./auto_sanity_test.sh

Reviewers: haobo, igor

Reviewed By: igor

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17397
Move several more logging inside DB mutex to log buffer

Summary: Move several some common logging still in DB mutex to log buffer.

Test Plan: make all check

Reviewers: haobo, igor, ljin, nkg-

Reviewed By: nkg-

CC: nkg-, yhchiang, leveldb

Differential Revision: https://reviews.facebook.net/D17439
initialize candidate count
[RocksDB] make SetPerfLevel affect only the current thread

Summary: as title, make it easy to turn on/off profiling at per thread level.

Test Plan: make check

Reviewers: sdong, ljin

Reviewed By: ljin

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17469
Fix MacOS errors
Fix some other signed & unsigned comparisons

Summary: Fix some signed and unsigned comparisons to make some other build script happy.

Test Plan: Build and run those changed tests

Reviewers: ljin, igor, haobo

Reviewed By: igor

CC: yhchiang, dhruba, kailiu, leveldb

Differential Revision: https://reviews.facebook.net/D17463
Update HISTORY.md

Summary: Update HISTORY.md to make existing items to 2.8 release and add something I think is missing.

Test Plan: N/A

Reviewers: haobo, igor, ljin, dhruba, yhchiang, xjin

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17517