perf test: Use strerror_r instead of strerror

Use strerror_r instead of strerror in error messages for thread-safety.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Naohiro Aota <naota@elisp.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20140814022245.3545.91394.stgit@kbuild-fedora.novalocal
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index c6796d2..9948136 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -185,9 +185,11 @@
 static int run_test(struct test *test)
 {
 	int status, err = -1, child = fork();
+	char sbuf[STRERR_BUFSIZE];
 
 	if (child < 0) {
-		pr_err("failed to fork test: %s\n", strerror(errno));
+		pr_err("failed to fork test: %s\n",
+			strerror_r(errno, sbuf, sizeof(sbuf)));
 		return -1;
 	}