Merge pull request swiftlang#883 from DougGregor/cmake-fix

Add new file to CMakeLists.txt

Author: DougGregor

Sources/SwiftDriver/CMakeLists.txt

@@ -26,6 +26,7 @@ add_library(SwiftDriver
  Driver/OutputFileMap.swift
  Driver/ToolExecutionDelegate.swift
  Driver/DriverVersion.swift
+ Driver/WindowsExtensions.swift
 
  Execution/ArgsResolver.swift
  Execution/DriverExecutor.swift