perf tools: Fix a compiling error in util/map.c

This patch fix a compile warning taken as error:

	CC util/map.o
	cc1: warnings being treated as errors
	util/map.c: In function ‘map__fprintf_dsoname’:
	util/map.c:240: error: ‘dsoname’ may be used uninitialized in this function
	make: *** [util/map.o] Error 1
Signed-off-by: NFeng Tang <feng.tang@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1346053107-11946-3-git-send-email-feng.tang@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/map.c

@@ -243,15 +243,14 @@ size_t map__fprintf(struct map *self, FILE *fp)
 
 size_t map__fprintf_dsoname(struct map *map, FILE *fp)
 {
-	const char *dsoname;
+	const char *dsoname = "[unknown]";
 
 	if (map && map->dso && (map->dso->name || map->dso->long_name)) {
 		if (symbol_conf.show_kernel_path && map->dso->long_name)
 			dsoname = map->dso->long_name;
 		else if (map->dso->name)
 			dsoname = map->dso->name;
-	} else
-		dsoname = "[unknown]";
+	}
 
 	return fprintf(fp, "%s", dsoname);
 }