Request for reviews (S): 7089632: assert(machtmp->outcnt() == 1) failed: expected for a MachTemp

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/7089632/webrev

7089632: assert(machtmp->outcnt() == 1) failed: expected for a MachTemp

The problem is spilling MachTemp and then removing intermediate MSC during 
postallocation in use_prior_register() so that MachTemp has additional use.

Replace assert with check to delete MachTemp nodes only when they are really dead.

Thanks,
Vladimir