libbb: eliminate a static data array in bb_mode_string()

function                                             old     new   delta
print_stat                                           861     869      +8
header_verbose_list_ar                                73      77      +4
display_single                                       975     979      +4
header_verbose_list                                  237     239      +2
bb_mode_string                                       124     115      -9
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/1 up/down: 18/-9)               Total: 9 bytes
   text	   data	    bss	    dec	    hex	filename
1043136	    559	   5052	1048747	 1000ab	busybox_old
1043153	    559	   5020	1048732	 10009c	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/coreutils/ls.c b/coreutils/ls.c
index 9e85616..9a1264e 100644
--- a/coreutils/ls.c
+++ b/coreutils/ls.c
@@ -503,7 +503,8 @@
 		column += printf("%6"OFF_FMT"u ", (off_t) (dn->dn_blocks >> 1));
 	if (opt & OPT_l) {
 		/* long listing: show mode */
-		column += printf("%-10s ", (char *) bb_mode_string(dn->dn_mode));
+		char modestr[12];
+		column += printf("%-10s ", (char *) bb_mode_string(modestr, dn->dn_mode));
 		/* long listing: show number of links */
 		column += printf("%4lu ", (long) dn->dn_nlink);
 		/* long listing: show user/group */