message: NFC: Remove old comment referencing CFG/EXT/ML functions.
diff: // limitations under the License.
  // =============================================================================
  //
  -// Functions are the basic unit of composition in MLIR. There are three
  -// different kinds of functions: external functions, CFG functions, and ML
  -// functions.
  +// Functions are the basic unit of composition in MLIR.
  //
  //===----------------------------------------------------------------------===//
  