We currently run these in swift-version 4 by default. This caused us to miss
some bugs that only occur in swift-version 5 due to initializer changes
happening in swift 5. This at least will allow us to catch such issues in the
future.
NOTE: I am also going to change objc_throwing_initializers.swift in the same
way, but after I fix the bugs that adding -swift-version 5 exposes therein
(which is actually <rdar://problem/59830255>)
This converts the instances of the pattern for which we have a proper
substitution in lit. This will make it easier to replace it
appropriately with Windows equivalents.