Fixed new bug when running a SP without a default database


mysql-test/r/information_schema.result:
  Added test to cover changes made in default handling
mysql-test/r/sp-security.result:
  Added test when executing SP without a default database
mysql-test/t/information_schema.test:
  Added test to cover changes made in default handling
mysql-test/t/sp-security.test:
  Added test when executing SP without a default database
sql/item_strfunc.cc:
  Removed wrong push
sql/mysqld.cc:
  Indentation fix
sql/sql_base.cc:
  Use share->db instead of share->table_cache_key
  Remove assert that can never fail (because of test in previous row)
sql/sql_db.cc:
  Allow empty database name when called from SP
  (To allow on run without a default database)
sql/sql_parse.cc:
  Added comment
sql/sql_show.cc:
  Indentation fixes
  Simplified code by checking for 'wrong' condition first and doing continue instead of going down one level
  Simplified precision and decimal handling