Summary:
sprintf is unsafe and has buffer overrun risk. Replace it with the safer version snprintf where buffer size is supplied to avoid overrun.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5475

Differential Revision: D15879481

Pulled By: sagar0

fbshipit-source-id: 7ae1958ffc9727fa50261dfbb98ddd74e70a72d8