usleep on BeOS

[sam th]

According to this email [1] snooze() preforms an identical function to
usleep() on Be.  So a simple ifdef/define should fix this issue easily.  

If someone tests this, I'll commit it.

[1] http://www.yabel.com/lists/beunited/0066.php3

                                sam th
                                [EMAIL PROTECTED]
                                http://www.abisource.com/~sam