perf buildid: Introduce sysfs/filename__sprintf_build_id

Introduce sysfs/filename__sprintf_build_id for consolidating similar
code.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
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/20150815114259.13642.34685.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-buildid-cache.c b/tools/perf/builtin-buildid-cache.c
index 65b4835..7b8450c 100644
--- a/tools/perf/builtin-buildid-cache.c
+++ b/tools/perf/builtin-buildid-cache.c
@@ -25,8 +25,6 @@
 static int build_id_cache__kcore_buildid(const char *proc_dir, char *sbuildid)
 {
 	char root_dir[PATH_MAX];
-	char notes[PATH_MAX];
-	u8 build_id[BUILD_ID_SIZE];
 	char *p;
 
 	strlcpy(root_dir, proc_dir, sizeof(root_dir));
@@ -35,15 +33,7 @@
 	if (!p)
 		return -1;
 	*p = '\0';
-
-	scnprintf(notes, sizeof(notes), "%s/sys/kernel/notes", root_dir);
-
-	if (sysfs__read_build_id(notes, build_id, sizeof(build_id)))
-		return -1;
-
-	build_id__sprintf(build_id, sizeof(build_id), sbuildid);
-
-	return 0;
+	return sysfs__sprintf_build_id(root_dir, sbuildid);
 }
 
 static int build_id_cache__kcore_dir(char *dir, size_t sz)
@@ -138,7 +128,7 @@
 		return -1;
 	*p = '\0';
 
-	if (build_id_cache__kcore_buildid(from_dir, sbuildid))
+	if (build_id_cache__kcore_buildid(from_dir, sbuildid) < 0)
 		return -1;
 
 	scnprintf(to_dir, sizeof(to_dir), "%s/[kernel.kcore]/%s",