tools: fix mq_open_tests compile warnings

Fix several compile warnings - these are repeats like the ones
below:

gcc -O2 -lrt mq_open_tests.c -o mq_open_tests
mq_open_tests.c: In function ‘main’:
mq_open_tests.c:295:2: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘rlim_t’ [-Wformat=]
  printf("\tRLIMIT_MSGQUEUE(soft):\t\t%d\n", saved_limits.rlim_cur);
  ^
mq_open_tests.c: In function ‘shutdown’:
mq_open_tests.c:83:9: warning: ignoring return value of ‘seteuid’, declared with attribute warn_unused_result [-Wunused-result]
  seteuid(0);

Signed-off-by: Shuah Khan <shuah.kh@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>