[IR] Rename the class templates for the case iterator and case handle to not collide with the naming convention for template *arguments*. In at least one case they actually collided and this confuses MSVC.
[IR] Rename the class templates for the case iterator and case handle to
not collide with the naming convention for template *arguments*. In at
least one case they actually collided and this confuses MSVC.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@300038 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm