Fix max_key_length and max_unique_length to take into account varchar and null extra lengths

This fixes a bug found by bdb.test
Fixes a portability issue with bdb tables

mysql-test/include/varchar.inc

@@ -77,6 +77,7 @@ explain select count(*) from t1 where v between 'a' and 'a ' and v between 'a  '
 alter table t1 add unique(v);
 alter table t1 add key(v);
 select concat('*',v,'*',c,'*',t,'*') as qq from t1 where v='a';
+--replace_column 6 #
 explain select * from t1 where v='a';
 
 # GROUP BY

mysql-test/r/bdb.result

@@ -1445,7 +1445,7 @@ qq
 *a         *a*a         *
 explain select * from t1 where v='a';
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	v,v_2	v	13	const	10	Using where
+1	SIMPLE	t1	ref	v,v_2	#	13	const	10	Using where
 select v,count(*) from t1 group by v limit 10;
 v	count(*)
 a
	1

mysql-test/r/myisam.result

@@ -716,7 +716,7 @@ qq
 *a         *a*a         *
 explain select * from t1 where v='a';
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	v,v_2	v_2	13	const	7	Using where
+1	SIMPLE	t1	ref	v,v_2	#	13	const	7	Using where
 select v,count(*) from t1 group by v limit 10;
 v	count(*)
 a
	1

sql/table.cc

@@ -262,11 +262,6 @@ int openfrm(THD *thd, const char *name, const char *alias, uint db_stat,
       }
       key_part->store_length=key_part->length;
     }
-    set_if_bigger(outparam->max_key_length,keyinfo->key_length+
-		  keyinfo->key_parts);
-    outparam->total_key_length+= keyinfo->key_length;
-    if (keyinfo->flags & HA_NOSAME)
-      set_if_bigger(outparam->max_unique_length,keyinfo->key_length);
   }
   keynames=(char*) key_part;
   strpos+= (strmov(keynames, (char *) strpos) - keynames)+1;
@@ -718,6 +713,12 @@ int openfrm(THD *thd, const char *name, const char *alias, uint db_stat,
 	}
       }
       keyinfo->usable_key_parts=usable_parts; // Filesort
+
+      set_if_bigger(outparam->max_key_length,keyinfo->key_length+
+                    keyinfo->key_parts);
+      outparam->total_key_length+= keyinfo->key_length;
+      if (keyinfo->flags & HA_NOSAME)
+        set_if_bigger(outparam->max_unique_length,keyinfo->key_length);
     }
     if (primary_key < MAX_KEY &&
 	(outparam->keys_in_use.is_set(primary_key)))