Cherry pick PRs from master#2012

Merged

rshriram merged 3 commits intoistio:release-1.1from

rshriram:release-1.1

Oct 30, 2018

Commits on Oct 30, 2018

Improve performance by removing MD5 for check cache keys (#2002)

qiwzhang
authored and
Shriram Rajagopalan
committed
alts: remove ALTS (#2003)

lizan
authored and
Shriram Rajagopalan
committed
Use std::hash for check cache. (#2009)

qiwzhang
authored and
Shriram Rajagopalan
committed