Fix xdump updates not to dump bogus extra updates

"xdump updates" believes there are always 15 (UPDATE_TIME_LEN - 1)
scheduled updates.  When fewer than 15 updates are scheduled, it shows
whatever crap update time happens to be in the unused part of
update_time[]: the initial zero or a previously scheduled update.

Root cause is that table EF_UPDATES has always UPDATE_TIME_LEN - 1
entries, which is incorrect when fewer updates are scheduled.  Only
xdump is affected, as the other users ignore the length and stop at
the sentinel.

Fix update_get_schedule() to resize table EF_UPDATES.

src/lib/common/filetable.c

@@ -186,7 +186,7 @@ struct empfile empfile[] = {
      * Update schedule table.  Use read_schedule() to fill.
      */
     {EF_UPDATES, "updates", NULL, update_ca,
-     ARRAY_TABLE(update_time, EFF_CFG)},
+     ARRAY_CACHE(update_time, EFF_CFG)},
     /*
      * Special tables.  EF_META gets bogus size, cids and fids here.
      * Fixed up by empfile_init().  EF_VERSION's cadef is set by