Attempt to fix static_asserts in SelectionDAGNodes.h that MSVC chokes on.
Attempt to fix static_asserts in SelectionDAGNodes.h that MSVC chokes on.

These were added in r281051, which, I am embarrassed to admit, has an
incomplete commit message that I forgot to update before pushing.  You
can ignore element (2) in that list.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@281054 91177308-0d34-0410-b5e6-96231b3b80d8

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