[ThinLTO] Remove missed piece of lazy summary reading support (NFC)
[ThinLTO] Remove missed piece of lazy summary reading support (NFC)

Missed in r267097.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@268597 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm