Fix memory errors in test_poll and test_queuemanager

test_poll was calling poll_init() two times since it's already included in
init_test_env().

test_queuemanager was missing a bunch of frees. This doesn't fix it completely,
but removes most of the leaks and valgrind errors.

server/core/test/testpoll.c

@@ -55,7 +55,6 @@ test1()
     ss_dfprintf(stderr,
                 "testpoll : Initialise the polling system.");
     init_test_env(NULL);
-    poll_init();
     ss_dfprintf(stderr, "\t..done\nAdd a DCB");
     dcb = dcb_alloc(DCB_ROLE_CLIENT_HANDLER, &dummy);