Excluding this test on unsupported platform

... based on Tyler's discovery at https://gist.github.com/rtyler/9195510

testRemoting(hudson.util.ProcessTreeTest)  Time elapsed: 0.097 sec  <<< ERROR!
java.util.NoSuchElementException: null
        at java.util.HashMap$HashIterator.nextEntry(HashMap.java:897)
        at java.util.HashMap$ValueIterator.next(HashMap.java:922)
        at hudson.util.ProcessTreeTest$MyCallable.call(ProcessTreeTest.java:42)
        at hudson.util.ProcessTreeTest$MyCallable.call(ProcessTreeTest.java:38)
        at hudson.remoting.UserRequest.perform(UserRequest.java:118)
        at hudson.remoting.UserRequest.perform(UserRequest.java:48)
        at hudson.remoting.Request$2.run(Request.java:328)
        at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
        at java.util.concurrent.FutureTask.run(FutureTask.java:166)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:724)

He runs this on FreeBSD.