perf top: Use strerror_r instead of strerror

Use strerror_r instead of strerror in error message 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/20140814022238.3545.15569.stgit@kbuild-fedora.novalocalSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-top.c

@@ -899,7 +899,7 @@ static int perf_top__start_counters(struct perf_top *top)
 
 	if (perf_evlist__mmap(evlist, opts->mmap_pages, false) < 0) {
 		ui__error("Failed to mmap with %d (%s)\n",
-			    errno, strerror(errno));
+			    errno, strerror_r(errno, msg, sizeof(msg)));
 		goto out_err;
 	}