[stdlib/cygwin] Removed the workaround of print() (SR-612)

Currently, in Cygwin, the print() function works well without any workaround.
I presume this bug is fixed by side effect of some other commit, but couldn't find out exactly what.

Author: tinysun212

stdlib/public/core/Print.swift

@@ -28,11 +28,6 @@ public func print(
   separator: String = " ",
   terminator: String = "\n"
 ) {
-#if os(Windows)
-  // FIXME: This fix is for 'crash at hook(output.left)' in cygwin.
-  //        Proper fix is needed. see: https://bugs.swift.org/browse/SR-612
-  let _playgroundPrintHook: ((String) -> Void)? = nil
-#endif
   if let hook = _playgroundPrintHook {
     var output = _TeeStream(left: "", right: _Stdout())
     _print(