perf evsel: Know if byte swap is needed

Instead of passing it around for parsing as an explicit parameter, will
help with reading tracepoint fields when not using a perf session or
pevent structure, i.e. for non perf.data centered workflows.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-qa67ikv2sm49cwa7dyjhhp6g@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 6aae329..7daad23 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1256,8 +1256,10 @@
 		if (ret != (ssize_t)sizeof(nr))
 			goto error;
 
-		if (ph->needs_swap)
+		if (ph->needs_swap) {
 			nr = bswap_32(nr);
+			evsel->needs_swap = true;
+		}
 
 		evsel->name = do_read_string(fd, ph);
 
@@ -2626,6 +2628,8 @@
 
 		if (evsel == NULL)
 			goto out_delete_evlist;
+
+		evsel->needs_swap = header->needs_swap;
 		/*
 		 * Do it before so that if perf_evsel__alloc_id fails, this
 		 * entry gets purged too at perf_evlist__delete().