Fix XEN build breakage, by implementing pmap_invalidate_cache_range() and using it when appropriate. Merge analogue of the r195836 optimization to XEN.
Fix XEN build breakage, by implementing pmap_invalidate_cache_range()
and using it when appropriate. Merge analogue of the r195836
optimization to XEN.

Approved by:	re (kensmith)

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase