Although the query cache doesn't support retrieval of statements containing
column level access control, it was still possible to cache such statements
thus wasting memory.

This patch extends the access control check on the target tables to avoid
caching a statement with column level restrictions. 


mysql-test/r/query_cache.result:
  Added test
mysql-test/t/query_cache.test:
  Added test
sql/sql_cache.cc:
  The function check_table_access leaves the artifact
  grant.want_privileges= 1, if a statement refers to tables with column level
  privileges. To avoid the statement from being stored into the query cache,
  it is enough to check this flag and set 'safe_to_cache_query' to zero.
sql/sql_cache.h:
  - Removed 'static' attribute or class methods
  - Added THD parameter to process_and_count_tables