ssl: socket.sendall(): trampoline if sent 0 bytes; fixes CPU burn

https://bitbucket.org/which_linden/eventlet/issue/134/greenssl-performance-issues

eventlet/green/ssl.py

@@ -130,6 +130,8 @@ class GreenSSLSocket(__ssl.SSLSocket):
             while (count < amount):
                 v = self.send(data[count:])
                 count += v
+                if v == 0:
+                    trampoline(self, write=True, timeout_exc=timeout_exc('timed out'))
             return amount
         else:
             while True: