perf util: Replace strerror with strerror_r for thread-safety

Replaces all strerror with strerror_r in util for making the perf lib
thread-safe.

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/20140814022236.3545.3367.stgit@kbuild-fedora.novalocal
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 25822bd..24e8d87 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -456,6 +456,7 @@
 	size_t size = 0, alloc_size = 0;
 	void *bf = NULL, *nbf;
 	int fd, n, err = 0;
+	char sbuf[STRERR_BUFSIZE];
 
 	fd = open(filename, O_RDONLY);
 	if (fd < 0)
@@ -476,8 +477,8 @@
 		n = read(fd, bf + size, alloc_size - size);
 		if (n < 0) {
 			if (size) {
-				pr_warning("read failed %d: %s\n",
-					   errno, strerror(errno));
+				pr_warning("read failed %d: %s\n", errno,
+					 strerror_r(errno, sbuf, sizeof(sbuf)));
 				err = 0;
 			} else
 				err = -errno;