perf tools: Initialize cpu set in pthread_attr_setaffinity_np feature test

Feature tests are compiled but not executed, however it might avoid a
future uninitialized variable warning, so initialize the cpu set.
Reported-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-tip-commits@vger.kernel.org
Link: http://lkml.kernel.org/r/54F41849.1010906@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/config/feature-checks/test-pthread-attr-setaffinity-np.c

 #include <stdint.h>
 #include <pthread.h>
+#include <sched.h>
 
 int main(void)
 {
@@ -8,7 +9,8 @@ int main(void)
 	cpu_set_t cs;
 
 	pthread_attr_init(&thread_attr);
-	/* don't care abt exact args, just the API itself in libpthread */
+	CPU_ZERO(&cs);
+
 	ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cs), &cs);
 
 	return ret;