[Polly][DCE] clang-format DeadCodeElimination.h. NFC.

The targets polly-update-format and check-polly-format process new files
only after running cmake again. This is why it was missed in the last
commit.

GitOrigin-RevId: 40653c8bb92c358137045e5610a713a9e00f6c14
1 file changed