swift234

stdlib: rename zip generator and collection to a common naming convention

  // Renamed from `ZipGenerator2`.
  struct Zip2Generator<Generator1 : GeneratorType, Generator2 : GeneratorType> { ... }

  // Renamed from `Zip2`.
  struct Zip2Sequence<Sequence1 : SequenceType, Sequence2 : SequenceType> { ... }

Part of rdar://21429126

Swift SVN r29636