windows: `listen(pipe_name)` is not supported when running cluster

- Added a note to the cluster module documentation.
- Disabled test-cluster-http-pipe.

doc/api/cluster.markdown

@@ -41,6 +41,9 @@ Running node will now share port 8000 between the workers:
 This feature was introduced recently, and may change in future versions.
 Please try it out and provide feedback.
 
+Also note that, on Windows, it is not yet possible to set up a named pipe
+server in a worker.
+
 ## How It Works
 
 <!--type=misc-->

test/simple/test-cluster-http-pipe.js

@@ -19,6 +19,11 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
+// It is not possible to send pipe handles over the IPC pipe on Windows.
+if (process.platform === 'win32') {
+  process.exit(0);
+}
+
 var common = require('../common');
 var assert = require('assert');
 var cluster = require('cluster');