Fix CompactFiles() bug when used with CompactionFilter using SuperVersion

Fix CompactFiles() bug when used with CompactionFilter using SuperVersion

Summary:
GetAndRefSuperVersion() should not be called again in the same thread before ReturnAndCleanupSuperVersion() is called.

If we have a compaction filter that is using DB::Get, This will happen
```
CompactFiles() {
  GetAndRefSuperVersion() // -- first call
    ..
    CompactionFilter() {
      GetAndRefSuperVersion() // -- second call
      ReturnAndCleanupSuperVersion()
    }
    ..
  ReturnAndCleanupSuperVersion()
}
```

We solve this issue in the same way Iterator is solving it, but using GetReferencedSuperVersion()

This was discovered in https://github.com/facebook/mysql-5.6/issues/427 by alxyang
Closes https://github.com/facebook/rocksdb/pull/1803

Differential Revision: D4460155

Pulled By: IslamAbdelRahman

fbshipit-source-id: 5e54322