Merge pull request swiftlang#39407 from DougGregor/concurrency-back-deploy-no-llvm-config

Author: swift-ci

stdlib/public/Concurrency/Actor.cpp

@@ -34,7 +34,14 @@
 #include "swift/Runtime/ThreadLocalStorage.h"
 #include "swift/ABI/Task.h"
 #include "swift/ABI/Actor.h"
+#ifndef SWIFT_CONCURRENCY_BACK_DEPLOYMENT
 #include "llvm/Config/config.h"
+#else
+// All platforms where we care about back deployment have a known
+// configurations.
+#define HAVE_PTHREAD_H 1
+#define SWIFT_OBJC_INTEROP 1
+#endif
 #include "llvm/ADT/PointerIntPair.h"
 #include "TaskPrivate.h"
 #include "VoucherSupport.h"