Add "#undef NDEBUG" to all tests.

This change makes sure that even if the tests are built in a
"release" configuration (with optimizations and NDEBUG turned on),
the assertions won't get compiled out of the tests themselves.

The C standard guarantees that the most recent inclusion of
<assert.h> is the one that counts, so it's important that the
"#undef NDEBUG/#include <assert.h>" come as the last thing in
the block of header files.

"testutil.hpp" includes <assert.h>, so I've left <assert.h> out
of any test that #includes "testutil.hpp", just for the sake of
brevity.

tests/test_term_endpoint.cpp

@@ -1,10 +1,31 @@
-#include <assert.h>
-#include <string.h>
-#include <unistd.h>
+/*
+    Copyright (c) 2010-2011 250bpm s.r.o.
+    Copyright (c) 2011 iMatix Corporation
+    Copyright (c) 2010-2011 Other contributors as noted in the AUTHORS file
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
 
 #include "../include/zmq.h"
 #include "../include/zmq_utils.h"
+#include <string.h>
+#include <unistd.h>
 
+#undef NDEBUG
+#include <assert.h>
 
 int main (void)
 {