quartz-wm: add cf-private

    Undefined symbols for architecture x86_64:
      "_CFNotificationCenterAddObserver", referenced from:
          _main in main.o
      "_CFNotificationCenterGetDistributedCenter", referenced from:
          _main in main.o
      "_OBJC_CLASS_$_NSTimer", referenced from:
          objc-class-ref in main.o
          objc-class-ref in x-screen.o
      "_OBJC_EHTYPE_$_NSException", referenced from:
          GCC_except_table25 in main.o
    ld: symbol(s) not found for architecture x86_64