[x86] Add a missing triple, without which the CPU won't parse.
[x86] Add a missing triple, without which the CPU won't parse.

Notably, this is failing on our PPC build bots:
http://lab.llvm.org:8011/builders/clang-ppc64le-linux/builds/8338/steps/ninja%20check%201/logs/FAIL%3A%20LLVM%3A%3Apr33772.ll

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@308272 91177308-0d34-0410-b5e6-96231b3b80d8

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