Descent for DOS supported paging content on demand. Rebirth has no
support for paging content out, but retained piggy_page_flushed
to track whether anything had been paged out. Commit 3c20c24 ("Disable
piggy_bitmap_page_out_all") removed the last site that could set
piggy_bitmap_page_out_all to a non-zero value. All remaining code
either tests it for non-zero or sets it to zero.
Remove the statements that set it to zero.
Remove assertions that the value is zero.
Remove conditional blocks that execute only when it is non-zero.
9d0c6f59a5