Fixed 'not initialized' memory error.


mysql-test/mysql-test-run.sh:
  Updates to be able to more easily use --valgrind
mysql-test/r/alter_table.result:
  Added missing drop table
mysql-test/t/alter_table.test:
  Added missing drop table
sql/field.cc:
  Simple optimizations
sql/ha_innodb.cc:
  Remove copying of parameters as this leads to memory leaks in MySQL.
  Should be instead fixed by, in embedded server, make a temporary copy of
  all parameters and free them on server-end
sql/log.cc:
  Simple optimization
sql/mysql_priv.h:
  Move external reference to struct to include file
sql/mysqld.cc:
  Added safety asserts
sql/sql_class.cc:
  Fixed non fatal 'not initialized memory reference error' in thread init
sql/sql_udf.cc:
  Clear current_thd for global thread
strings/strto.c:
  Simple optimization