Add site.exp and dejagnu board config

Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
libgloss/or1k: replace NOP_EXIT_SILENT with NOP_EXIT

Use NOP_EXIT because NOP_EXIT_SILENT break the gdb testsuite
using or1ksim.

http://www.mail-archive.com/openrisc@lists.openrisc.net/msg00636.html

Signed-off-by: Franck Jullien <franck.jullien@gmail.com>