Problem: executing queries like "ALTER TABLE view1;" we don't
check new view's name (which is not specified),
that leads to server crash.

Fix: do nothing (to be consistent with the behaviour for tables) 
in such cases.


mysql-test/r/view.result:
  Fix for bug#44860: ALTER TABLE on view crashes server
    - test result.
mysql-test/t/view.test:
  Fix for bug#44860: ALTER TABLE on view crashes server
    - test case.
sql/sql_rename.cc:
  Fix for bug#44860: ALTER TABLE on view crashes server
    - do_rename(): new view/table name must be specified, ASSERT() added.
sql/sql_table.cc:
  Fix for bug#44860: ALTER TABLE on view crashes server
    - mysql_alter_table(): renaming a view, check if new
  view name is specified.