Test server exits gracefully at command of test client

test/testclnt.lua

@@ -662,6 +662,9 @@ local udp_methods = {
     "setsockname",
     "settimeout"
 }
+
+
+------------------------------------------------------------------------
 test_methods(socket.udp(), udp_methods)
 test_methods(socket.udp6(), udp_methods)
 
@@ -785,4 +788,8 @@ test_blockingtimeoutreceive(800091, 2, 3)
 test_blockingtimeoutreceive(800091, 3, 2)
 test_blockingtimeoutreceive(800091, 3, 1)
 
+test("shutting server down")
+reconnect()
+remote("os.exit()")
+
 test(string.format("done in %.2fs", socket.gettime() - start))