clang-refactor-test: dispose of the TU
clang-refactor-test: dispose of the TU

rdar://35618000

apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang