Use a twiddle to show that we're busy dumping. The initial code

Use a twiddle to show that we're busy dumping. The initial code
emitted the total number of pages it still had to dump prior to
dumping a block of up to 16 pages. For a 128MB region this would
result in 8M number of printf()s. Barf!

The problem in general is that memory typically has one really
big region and a number of "scattered" smaller regions. Some may
even be just a few pages. The twiddle works best for now, but
it doesn't really give a good progress indication for the large
regions. Those are the cases where you definitely want good PI
to avoid having the user turn into a twiddle :-)