For LOCK view is opened but not prepared thus leaving 'table' field set to
NULL. invalidate_locked_for_write() wasn't checking that and call to 
invalidate_table(NULL) crashes server.

To invalidate_locked_for_write() added check that ensures that table is
completely opened.


sql/sql_cache.cc:
  Fix bug #13424 locking view with query cache enabled crashes server
  Added check that table is completely opened.
mysql-test/t/view_query_cache.test:
  Test case for bug#13424 locking view with query cache enabled crashes server
mysql-test/r/view_query_cache.result:
  Test case for bug#13424 locking view with query cache enabled crashes server