Fixed one warning and two errors reported by VC 6.0.

BitKeeper/etc/ignore:
  Added ndb/tools/ndb_restore to the ignore list
sql/item.cc:
  Fixed VC 6.0 warning:
  mysql-5.0.2-alpha\sql\item.cpp(1729) : warning C4715: 'resolve_ref_in_select_and_group' : not all control paths return a value
sql/opt_range.cc:
  Fixed VC 6.0 errors:
  ERROR # 4: mysql-5.0.2-alpha\sql\opt_range.cpp(8070) : error C2664: 'key_cmp' : cannot convert parameter 2 from 'char *' to 'const unsigned char *'
          Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
  
  ERROR # 5: mysql-5.0.2-alpha\sql\opt_range.cpp(8196) : error C2664: 'key_cmp' : cannot convert parameter 2 from 'char *' to 'const unsigned char *'
          Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

.bzrignore

@@ -960,3 +960,4 @@ vio/test-sslclient
 vio/test-sslserver
 vio/viotest-ssl
 ac_available_languages_fragment
+ndb/tools/ndb_restore

sql/item.cc

@@ -1722,7 +1722,10 @@ resolve_ref_in_select_and_group(THD *thd, Item_ident *ref, SELECT_LEX *select)
     else if (group_by_ref)
       return group_by_ref;
     else
+    {
       DBUG_ASSERT(FALSE);
+      return NULL; /* So there is no compiler warning. */
+    }
   }
   else
     return (Item**) not_found_item;

sql/opt_range.cc

@@ -8066,7 +8066,7 @@ int QUICK_GROUP_MIN_MAX_SELECT::next_min_in_range()
       boundary of cur_range, there is no need to check this range.
     */
     if (range_idx != 0 && !(cur_range->flag & NO_MAX_RANGE) &&
-        (key_cmp(min_max_arg_part, (byte*) cur_range->max_key,
+        (key_cmp(min_max_arg_part, (const byte*) cur_range->max_key,
                  min_max_arg_len) == 1))
       continue;
 
@@ -8193,7 +8193,7 @@ int QUICK_GROUP_MIN_MAX_SELECT::next_max_in_range()
     */
     if (range_idx != min_max_ranges.elements &&
         !(cur_range->flag & NO_MIN_RANGE) &&
-        (key_cmp(min_max_arg_part, (byte*) cur_range->min_key,
+        (key_cmp(min_max_arg_part, (const byte*) cur_range->min_key,
                  min_max_arg_len) == -1))
       continue;