mysql-test/r/query_cache.result:
  test of query_cache_min_res_unit
mysql-test/t/query_cache.test:
  test of query_cache_min_res_unit
sql/mysql_priv.h:
  made variable query_cache_min_res_unit from QUERY_CACHE_MIN_RESULT_DATA_SIZE
sql/mysqld.cc:
  made variable query_cache_min_res_unit from QUERY_CACHE_MIN_RESULT_DATA_SIZE
sql/set_var.cc:
  made variable query_cache_min_res_unit from QUERY_CACHE_MIN_RESULT_DATA_SIZE
sql/sql_cache.cc:
  method for parameter changing
sql/sql_cache.h:
  method for parameter changing