procedure variable
  Second version, after review.
  Keep the unsigned_flag in Item_decimal updated. Note that this also changed
  the result of several old test results - creating tables from decimal
  templates now gives unsigned columns and different sizes. (Several tests
  had Length > Max_length before.)


mysql-test/r/case.result:
  Updated result (after fixing BUG#12589).
mysql-test/r/metadata.result:
  Updated result (after fixing BUG#12589).
mysql-test/r/ps_2myisam.result:
  Updated result (after fixing BUG#12589).
mysql-test/r/ps_3innodb.result:
  Updated result (after fixing BUG#12589).
mysql-test/r/ps_4heap.result:
  Updated result (after fixing BUG#12589).
mysql-test/r/ps_5merge.result:
  Updated result (after fixing BUG#12589).
mysql-test/r/ps_6bdb.result:
  Updated result (after fixing BUG#12589).
mysql-test/r/ps_7ndb.result:
  Updated result (after fixing BUG#12589).
mysql-test/r/sp.result:
  New test case for BUG#12589.
mysql-test/r/type_newdecimal.result:
  Updated result (after fixing BUG#12589).
mysql-test/t/sp.test:
  New test case for BUG#12589.
sql/item.cc:
  Keep the unsigned_flag updated in Item_splocal and Item_decimal.