selftests: Uninitialized variable in test_cgcore_proc_migration()

The "c_threads" variable is used in the error handling code before it
has been initialized

Fixes: 11318989c381 ("selftests: cgroup: Add task migration tests")
Signed-off-by: Dan Carpenter <[e-mail]>
Acked-by: Michal Koutný <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/cgroup/test_core.c

···
 static int test_cgcore_proc_migration(const char *root)
 {
 	int ret = KSFT_FAIL;
-	int t, c_threads, n_threads = 13;
+	int t, c_threads = 0, n_threads = 13;
 	char *src = NULL, *dst = NULL;
 	pthread_t threads[n_threads];