Stop re-exporting SwiftNativeNSObject in libswift_Concurrency.

We can't start doing this now.

(cherry picked from commit 5868ae9)

Author: DougGregor

stdlib/public/CMakeLists.txt

@@ -4,7 +4,6 @@ set(SWIFT_RUNTIME_CXX_FLAGS)
 set(SWIFT_RUNTIME_LINK_FLAGS)
 set(SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS)
 set(SWIFT_RUNTIME_SWIFT_LINK_FLAGS)
-set(SWIFT_RUNTIME_CONCURRENCY_SWIFT_LINK_FLAGS)
 
 if(SWIFT_RUNTIME_USE_SANITIZERS)
   # TODO: Refactor this
@@ -117,10 +116,3 @@ if(SWIFT_BUILD_SDK_OVERLAY)
     add_subdirectory(Windows)
   endif()
 endif()
-
-if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
-  list(APPEND SWIFT_RUNTIME_CONCURRENCY_SWIFT_LINK_FLAGS
-    "-Wl,-reexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/Concurrency/ReexportedSymbols")
-endif()
-
-list(APPEND SWIFT_RUNTIME_CONCURRENCY_SWIFT_LINK_FLAGS "${SWIFT_RUNTIME_SWIFT_LINK_FLAGS}")

stdlib/public/Concurrency/CMakeLists.txt

@@ -121,7 +121,6 @@ add_swift_target_library(swift_Concurrency ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} I
     -Xfrontend -define-availability
     -Xfrontend "SwiftStdlib 5.5:macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0"
     ${SWIFT_RUNTIME_CONCURRENCY_SWIFT_FLAGS}
-  LINK_FLAGS "${SWIFT_RUNTIME_CONCURRENCY_SWIFT_LINK_FLAGS}"
   ${swift_concurrency_options}
   INSTALL_IN_COMPONENT ${swift_concurrency_install_component}
 )