message: repl: correct linking against `libdl`
  Not all targets link against libdl.  NetBSD is one such target.  Use
  `CMAKE_DL_LIBS` which will correctly specify the spelling as well as
  configure the value as appropriate for the target.
diff: @@ -7,10 +7,10 @@ elseif( CMAKE_SYSTEM_NAME MATCHES "Linux" )
  # Set the correct rpath to locate libswiftCore
  if (CMAKE_HOST_SYSTEM_PROCESSOR MATCHES "ppc64le")
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} \
  - -Wl,-rpath,${CMAKE_BINARY_DIR}/../swift-linux-powerpc64le/lib${LLVM_LIBDIR_SUFFIX}/swift/linux/powerpc64le -Wl,-ldl")
  + -Wl,-rpath,${CMAKE_BINARY_DIR}/../swift-linux-powerpc64le/lib${LLVM_LIBDIR_SUFFIX}/swift/linux/powerpc64le")
  else()
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} \
  - -Wl,-rpath,${CMAKE_BINARY_DIR}/../swift-linux-x86_64/lib${LLVM_LIBDIR_SUFFIX}/swift/linux -Wl,-ldl")
  + -Wl,-rpath,${CMAKE_BINARY_DIR}/../swift-linux-x86_64/lib${LLVM_LIBDIR_SUFFIX}/swift/linux")
  endif()
  set(CMAKE_INSTALL_RPATH "$ORIGIN/../lib/swift/linux:${CMAKE_INSTALL_RPATH}")
  endif()
  @@ -18,6 +18,7 @@ endif()
  add_lldb_tool(repl_swift
  main.c
  )
  +target_link_libraries(repl_swift PRIVATE ${CMAKE_DL_LIBS})
  # The dummy repl executable is a C program, but we always look for a mangled
  # swift symbol (corresponding to main). If we build the repl with debug info,
  