[release-branch.go1] lib9: fix warning under clang 3.1

««« backport 73a10f76098b
lib9: fix warning under clang 3.1

Fixes #3534.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6035054

»»»

src/lib9/ctime.c

@@ -16,8 +16,8 @@ p9ctime(long t)
 	tt = t;
 	tm = localtime(&tt);
 	snprint(buf, sizeof buf, "%3.3s %3.3s %02d %02d:%02d:%02d %3.3s %d\n",
-		"SunMonTueWedThuFriSat"+(tm->tm_wday*3),
-		"JanFebMarAprMayJunJulAugSepOctNovDec"+(tm->tm_mon*3),
+		&"SunMonTueWedThuFriSat"[tm->tm_wday*3],
+		&"JanFebMarAprMayJunJulAugSepOctNovDec"[tm->tm_mon*3],
 		tm->tm_mday,
 		tm->tm_hour,
 		tm->tm_min,