Enlarge the race window for some test cases

These changes cause an assertion in lb_sendpipe() when executing the test_security_plain testcase.

tests/test_hwm.cpp

@@ -255,7 +255,9 @@ int test_inproc_bind_and_close_first (int send_hwm, int /* recv_hwm */)
 int main (void)
 {
     setup_test_environment();
-    
+
+	no_race_tests_please() ;
+
     int count;
 
     // Default values are 1000 on send and 1000 one receive, so 2000 total

tests/test_proxy.cpp

@@ -222,6 +222,8 @@ int main (void)
 {
     setup_test_environment ();
 
+	no_race_tests_please() ;
+
     void *ctx = zmq_ctx_new ();
     assert (ctx);
     // Control socket receives terminate command from main over inproc

tests/testutil.hpp

@@ -263,6 +263,12 @@ void setup_test_environment()
     _CrtSetReportFile( _CRT_ASSERT, _CRTDBG_FILE_STDERR );
 #   endif
 #endif
+	zmq_lb_race_window_2_size = 1 ;
+}
+
+void no_race_tests_please()
+{
+	zmq_lb_race_window_2_size = 0 ;
 }
 
 //  Provide portable millisecond sleep