[ADT] NFC: Fix bogus StringSwitch rule-of-five boilerplate
[ADT] NFC: Fix bogus StringSwitch rule-of-five boilerplate

Now that 'Str' is constant, the rule-of-file logic needs updating.

Reported by: vit9696@avp.su
Reviewed by: jordan_rose@apple.com

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@328803 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit cc1c5db7cf752a461c9a9121580106d1d5c91f3c)

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