test.py: (fixes #2743) Treat memory leaks as errors without parsing valgrind output

Valgrinds prints LEAK SUMMARY even if leak is suppressed.  Instead of
parsing valgrind output, which is error prone, it is possible to make
valgrind treat leaks as errors by passing "--show-leak-kinds=all"
argument.

test.py

@@ -754,7 +754,7 @@ def run_job_synchronously(shell_command, directory, valgrind, is_python, build_p
             path_cmd = os.path.join (NS3_BUILDDIR, shell_command)
 
     if valgrind:
-        cmd = "valgrind --suppressions=%s --leak-check=full --show-reachable=yes --error-exitcode=2 %s" % (suppressions_path, 
+        cmd = "valgrind --suppressions=%s --leak-check=full --show-reachable=yes --error-exitcode=2 --errors-for-leak-kinds=all %s" % (suppressions_path,
             path_cmd)
     else:
         cmd = path_cmd
@@ -781,18 +781,6 @@ def run_job_synchronously(shell_command, directory, valgrind, is_python, build_p
         print(stderr_results)
         retval = 1
 
-    #
-    # valgrind sometimes has its own idea about what kind of memory management
-    # errors are important.  We want to detect *any* leaks, so the way to do 
-    # that is to look for the presence of a valgrind leak summary section.
-    #
-    # If another error has occurred (like a test suite has failed), we don't 
-    # want to trump that error, so only do the valgrind output scan if the 
-    # test has otherwise passed (return code was zero).
-    #
-    if valgrind and retval == 0 and "== LEAK SUMMARY:" in stderr_results:
-        retval = 2
-    
     if options.verbose:
         print("Return code = ", retval)
         print("stderr = ", stderr_results)