Various tidying changes accumulated during that effort. They're all
functionally independent afaict, but there may be contextual
interactions between some of them.

1: paging: fold HAP and shadow memory alloc related fields
2: paging: fold most HAP and shadow final teardown
3: paging: move update_paging_modes() hook
4: paging: move and conditionalize flush_tlb() hook
5: PV: drop dead paging_update_paging_modes() call during Dom0 construction
6: shadow: adjust and move sh_type_to_size[]
7: shadow: don't open-code copy_domain_page()
8: shadow: drop zero initialization from shadow_domain_init()

Jan