Make max title length configurable, or allow truncation of original process title

[dominics]

At the moment, only up to MAX_TITLE_LENGTH characters of the process title are overwritten, but the rest of the former process title remains.

$ cat test.php
<?php
  setproctitle('01234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789');
  sleep(20);

$ php test.php This is the original process name, and the first part is overwritten, but the part at the end here will still remain in the process title
[...]
$ ps aux | grep 01234
user   21183  0.2  1.5 240464 15376 pts/3    T    00:41   0:00 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456 n in the process title