Skip sigchld test on windows [skip ci]

greentest/test__monkey_sigchld_2.py

@@ -15,18 +15,19 @@ def handle(*args):
         # This is the opposite of gunicorn.
         os.waitpid(-1, os.WNOHANG)
 # The signal watcher must be installed *before* monkey patching
-signal.signal(signal.SIGCHLD, handle)
+if hasattr(signal, 'SIGCHLD'):
+    signal.signal(signal.SIGCHLD, handle)
 
-pid = os.fork()
+    pid = os.fork()
 
-if pid: # parent
+    if pid: # parent
         try:
             _, stat = os.waitpid(pid, 0)
         except OSError:
             # Interrupted system call
             _, stat = os.waitpid(pid, 0)
         assert stat == 0, stat
-else:
+    else:
         import gevent.monkey
         gevent.monkey.patch_all()
         signal.signal(signal.SIGCHLD, signal.SIG_DFL)
@@ -40,3 +41,5 @@ else:
         f.close()
 
         sys.exit(0)
+else:
+    print("No SIGCHLD, not testing")