perf trace: We need to consider "nr" if "__syscall_nr" is not there

To cope with older kernels that don't have this patch backported:

  026842d ("tracing/syscalls: Rename "/format" tracepoint field name "nr" to "__syscall_nr:")

This makes 'perf trace' work again in RHEL7 kernels.

Cc: Taeung Song <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Wang Nan <[email protected]>
Link: https://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: acmel

tools/perf/builtin-trace.c

@@ -258,7 +258,8 @@ static int perf_evsel__init_syscall_tp(struct perf_evsel *evsel)
 	struct syscall_tp *sc = evsel->priv = malloc(sizeof(struct syscall_tp));
 
 	if (evsel->priv != NULL) {
-		if (perf_evsel__init_tp_uint_field(evsel, &sc->id, "__syscall_nr"))
+		if (perf_evsel__init_tp_uint_field(evsel, &sc->id, "__syscall_nr") &&
+		    perf_evsel__init_tp_uint_field(evsel, &sc->id, "nr"))
 			goto out_delete;
 		return 0;
 	}