Removed unused function patch_memory_storage_t::load_block_patch_list.
Removed patch_memory_storage_t::first_patch.
Added comment noting that patch_map is always empty.
Made apply_patch just ensure_flush all the time, dropped patch_memory_storage_t::store_patch.
Made patch_memory_storage_t assert that patch_map cannot be modified.  It seemingly cannot.
Marked patch_memory_storage_t::patch_map const to convincingly show that it is empty.
Removed calls to patch_memory_storage_t::has_patches_for_block and related calls that are no longer used.
Removed use of apply_patches (which was a nop).
Removed last_patch_materialized_or_zero.
Removed uses of get_patches_serialized_size.
Removed patch_memory_storage_t::drop_patches, which was effectively unused.
Made patch_memory_storage_t be an empty class.
Dropped patch_memory_storage files.
Removed useless last_patch_materialized_ variable.