[clang-format][NFC] Include TableGen in enum->string mapping used for debugging
[clang-format][NFC] Include TableGen in enum->string mapping used for debugging

Running `clang-format -debug` prints "Unknown" for tablegen files because of this missing mapping, even though it is recognized as a tablegen file.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@356097 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang