MDEV-14183: aria_pack segfaults in compress_maria_file

Column definition order in st_maria_share::columndef can differ from
order of fields in record(see also st_maria_share::column_nr,
st_maria_columndef::column_nr, _ma_column_nr_write(),
_ma_column_nr_read()). This was not taken into account in aria_pack
tool.

The fix is to initialize elements of HUFF_COUNTS array in the correct
order.

mysql-test/suite/maria/aria_pack_mdev14183.result

+CREATE TABLE `t` (
+`col_1` varchar(255) NOT NULL DEFAULT '',
+`col_2` varchar(255) NOT NULL,
+`col_3` int(11) NOT NULL DEFAULT '0',
+`col_4` int(11) NOT NULL DEFAULT '0'
+) ENGINE=Aria;
+insert into t values
+('foobar','qux',0,0),('abcdef','qux',0,0);
+Compressing test/t.MAD: (2 records)
+- Calculating statistics
+
+normal:      0  empty-space:       0  empty-zero:         0  empty-fill:   0
+pre-space:   0  end-space:         0  intervall-fields:   0  zero:         2
+Original trees:  4  After join: 1
+- Compressing file
+Min record length:      5   Max length:      5   Mean total length:     35
+99.57%     
+SELECT * FROM t;
+col_1	col_2	col_3	col_4
+foobar	qux	0	0
+abcdef	qux	0	0
+DROP TABLE t;

mysql-test/suite/maria/aria_pack_mdev14183.test

+--source include/have_aria.inc
+--source include/have_debug.inc
+
+CREATE TABLE `t` (
+  `col_1` varchar(255) NOT NULL DEFAULT '',
+  `col_2` varchar(255) NOT NULL,
+  `col_3` int(11) NOT NULL DEFAULT '0',
+  `col_4` int(11) NOT NULL DEFAULT '0'
+) ENGINE=Aria;
+
+insert into t values
+  ('foobar','qux',0,0),('abcdef','qux',0,0);
+
+--let $datadir= `SELECT @@datadir`
+--source include/shutdown_mysqld.inc
+# maria_pack crashes by assert() if the bug is not fixed
+--exec cd $datadir && $MARIA_PACK -t test/t
+
+--source include/start_mysqld.inc
+SELECT * FROM t;
+
+DROP TABLE t;

storage/maria/maria_pack.c

@@ -782,27 +782,29 @@ static HUFF_COUNTS *init_huff_count(MARIA_HA *info,my_off_t records)
     for (i=0 ; i < info->s->base.fields ; i++)
     {
       enum en_fieldtype type;
-      count[i].field_length=info->s->columndef[i].length;
-      type= count[i].field_type= (enum en_fieldtype) info->s->columndef[i].type;
+      uint col_nr = info->s->columndef[i].column_nr;
+      count[col_nr].field_length=info->s->columndef[i].length;
+      type= count[col_nr].field_type=
+        (enum en_fieldtype) info->s->columndef[i].type;
       if (type == FIELD_INTERVALL ||
 	  type == FIELD_CONSTANT ||
 	  type == FIELD_ZERO)
 	type = FIELD_NORMAL;
-      if (count[i].field_length <= 8 &&
+      if (count[col_nr].field_length <= 8 &&
 	  (type == FIELD_NORMAL ||
 	   type == FIELD_SKIP_ZERO))
-	count[i].max_zero_fill= count[i].field_length;
+	count[col_nr].max_zero_fill= count[col_nr].field_length;
       /*
         For every column initialize a tree, which is used to detect distinct
         column values. 'int_tree' works together with 'tree_buff' and
         'tree_pos'. It's keys are implemented by pointers into 'tree_buff'.
         This is accomplished by '-1' as the element size.
       */
-      init_tree(&count[i].int_tree,0,0,-1,(qsort_cmp2) compare_tree, NULL,
+      init_tree(&count[col_nr].int_tree,0,0,-1,(qsort_cmp2) compare_tree, NULL,
 		NULL, MYF(0));
       if (records && type != FIELD_BLOB && type != FIELD_VARCHAR)
-	count[i].tree_pos=count[i].tree_buff =
-	  my_malloc(count[i].field_length > 1 ? tree_buff_length : 2,
+	count[col_nr].tree_pos=count[col_nr].tree_buff =
+	  my_malloc(count[col_nr].field_length > 1 ? tree_buff_length : 2,
 		    MYF(MY_WME));
     }
   }