perf test: Fix build failure

perf test: Fix build failure

The commit 6a6cd11d4e57 ("perf test: Add test for the sched tracepoint
format fields") added following build error:

    CC builtin-test.o
  builtin-test.c: In function ‘perf_evsel__test_field’:
  builtin-test.c:1216:6: error: variable ‘ret’ set but not used [-Werror=unused-but-set-variable]
  builtin-test.c: In function ‘perf_evsel__tp_sched_test’:
  builtin-test.c:1242:6: error: variable ‘ret’ set but not used [-Werror=unused-but-set-variable]
  cc1: all warnings being treated as errors
  make: *** [builtin-test.o] Error 1

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1348539628-3821-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>