fix bug, current_program_name str add '\0' in the end
Merge remote-tracking branch 'origin/master'
fix bug, set current_program_name pointer to NULL after my_free
Merge remote-tracking branch 'origin/master'
1. tmysqldump performance enhancement
in function check_if_ignore_table, use "show table status like '$table_name'" to check table engine, now we use "select table_name, engine from information_schema.tables where table_schema='$db' and table_name='$tbl'" instead, which is much quickly.

2. reduce constant variable MAX_CLIENT_PROGRAM_NAME to 512(which is 1024 in version tmysql 1.2)