The SGI 3.40 PROM includes a fix for the move of the init_task to region 5, so 
specify that in sn_sal.h.  Unfortunately, the check for the minimum required 
version happens *after* the hang/MCA that is symptomatic of the bug, so this 
message also acts as an announcement of the requirement.

Signed-off-by: Jesse Barnes <jbarnes@sgi.com>

Jesse