[swift-dev] [Swift 2.2] IRGen: Don't try to bind witness tables for archetype protocol requirements that don't need them.

[Joe Groff]

Hey Joe, I'm testing a fix for a crash regression reported on Swift 2.2 as rdar://problem/24568361. I'd like to get this cherry-picked into the 2.2 branch.

https://github.com/apple/swift/pull/1245

-Joe