amd64 similar to i386. This fixes a bug on amd64 where overlapping
entries would not cause the SMAP parsing to stop.
- Change the SMAP parsing code to do a sorted insertion into physmap[]
instead of an append to support systems with out-of-order SMAP entries.
PR: amd64/138220
Reported by: James R. Van Artsdalen james of jrv org
MFC after: 3 days