perf symbols: Fix return value when loading PE DSO

The first time dso__load() was called on a PE file it always returned -1
error. This caused the first call to map__find_symbol() to always fail
on a PE file so the first sample from each PE file always had symbol
<unknown>. Subsequent samples succeed however because the DSO is already
loaded.

This fixes dso__load() to return 0 when successfully loading a DSO with
libbfd.

Fixes: eac9a434 ("perf symbols: Try reading the symbol table with libbfd")
Signed-off-by: NNicholas Fraser <nfraser@codeweavers.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Huw Davies <huw@codeweavers.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kim Phillips <kim.phillips@amd.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Remi Bernon <rbernon@codeweavers.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Tommi Rantala <tommi.t.rantala@nokia.com>
Cc: Ulrich Czekalla <uczekalla@codeweavers.com>
Link: http://lore.kernel.org/lkml/1671b43b-09c3-1911-dbf8-7f030242fbf7@codeweavers.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/symbol.c

@@ -1860,8 +1860,10 @@ int dso__load(struct dso *dso, struct map *map)
 		if (nsexit)
 			nsinfo__mountns_enter(dso->nsinfo, &nsc);
 
-		if (bfdrc == 0)
+		if (bfdrc == 0) {
+			ret = 0;
 			break;
+		}
 
 		if (!is_reg || sirc < 0)
 			continue;