aliases ignored
When a column reference to a column in JOIN USING is resolved and a new 
Item is created for this column the user defined name was lost.
This fix preserves the alias by setting the name of the new Item to the
original alias.


mysql-test/r/join.result:
  BUG#25106: A USING clause in combination with a VIEW results in column
             aliases ignored
   - test case
mysql-test/t/join.test:
  BUG#25106: A USING clause in combination with a VIEW results in column
             aliases ignored
   - test case
sql/sql_base.cc:
  BUG#25106: A USING clause in combination with a VIEW results in column
             aliases ignored
   - take the alias of the Item to be replaced and set it into the newly
     allocated Item.