Tag 7.6.0 release

Bump version.h to 7.5.3

Tagging v7.4.5

Tagging 7.4.4 public release

Tag public release v7.4.3

Tag v7.3.1

Tag a build on mainline; note this is *not* production-ready

Update HISTORY.md and version.h to 7.2.2

Add release note for facebook#9747 (facebook#9874)

Summary:
Add release note for CompressedSecondaryCache and the update of SecondaryCache::Lookup().

Pull Request resolved: facebook#9874

Reviewed By: jay-zhuang

Differential Revision: D35765973

Pulled By: gitbw95

fbshipit-source-id: 98232508c4f2047216def9c11a038cfb98709690

Tag v7.1.2