*: better string sharing

   text   data    bss    dec    hex filename
 849427    441   7556 857424  d1550 busybox_old
 849355    441   7556 857352  d1508 busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/archival/libunarchive/decompress_unxz.c b/archival/libunarchive/decompress_unxz.c
index 3f93929..1302e29 100644
--- a/archival/libunarchive/decompress_unxz.c
+++ b/archival/libunarchive/decompress_unxz.c
@@ -86,7 +86,7 @@
 		if (rd) {
 			rd = safe_read(src_fd, membuf + insz, rd);
 			if (rd < 0) {
-				bb_error_msg("read error");
+				bb_error_msg(bb_msg_read_error);
 				total = -1;
 				break;
 			}