swift234

[Serialization] Move (Module)Status and validateSerializedAST into a namespace.

Also into a separate file.

Before (swift/Serialization/SerializedModuleLoader.h):
  ModuleStatus
  SerializedModuleLoader::ValidationInfo
  SerializedModuleLoader::ExtendedValidationInfo
  SerializedModuleLoader::isSerializedAST
  SerializedModuleLoader::validateSerializedAST

After (swift/Serialization/Validation.h):
  serialization::Status
  serialization::ValidationInfo
  serialization::ExtendedValidationInfo
  serialization::isSerializedAST
  serialization::validateSerializedAST

No functionality change, just a lot of renaming and a bit of reorganizing.

Swift SVN r25226