Use random port numbers in dejagnu tests for nSIM, increase value of allowed reboots.

2013-05-31  Anton Kolesov <anton.kolesov@synopsys.com>

    * get-random-port.sh: Script that returns random port number that is free.
    * dejagnu/nsim-extra.exp, dejagnu/baseboards/arc-nsim.exp: Use
    get-random-port.sh instead of incremented ports and set very big
    max_reload_reboots value.