perf kvm stat live: Use perf_evlist__add_pollfd return fd position

With the interface changed in following commit:

  2171a925 tools lib fd array: Allow associating an integer cookie with each entry

the perf_evlist__add_pollfd function now returns the fd position in the
pollfd array.

Hence we no longer need to count the fd position, because we get it as
the return value.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Milian Wolff <mail@milianw.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1412179229-19466-4-git-send-email-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-kvm.c

@@ -933,10 +933,10 @@ static int kvm_events_live_report(struct perf_kvm_stat *kvm)
 
 	nr_fds++;
 
-	if (perf_evlist__add_pollfd(kvm->evlist, fileno(stdin)) < 0)
+	nr_stdin = perf_evlist__add_pollfd(kvm->evlist, fileno(stdin));
+	if (nr_stdin < 0)
 		goto out;
 
-	nr_stdin = nr_fds;
 	nr_fds++;
 	if (fd_set_nonblock(fileno(stdin)) != 0)
 		goto out;