Merge pull request #68029 from etcwilde/ewilde/delete-backdeploy-concurrency

Delete backdeploy concurrency library

Author: etcwilde

CMakeLists.txt

@@ -1289,11 +1289,6 @@ else()
     endif()
   endif()
 
-  if (BUILD_SWIFT_CONCURRENCY_BACK_DEPLOYMENT_LIBRARIES)
-    # Build the back-deployed concurrency library.
-    add_subdirectory(stdlib/public/BackDeployConcurrency)
-  endif()
-
   # Some tools (e.g. swift-reflection-dump) rely on a host swiftRemoteInspection,
   # so ensure we build that when building tools.
   if(SWIFT_INCLUDE_TOOLS OR SWIFT_BUILD_STDLIB_CXX_MODULE)