Fixed some bugs we introduced by incorrectly double-accounting the PFN database....

Fixed some bugs we introduced by incorrectly double-accounting the PFN database. The database is *virtually* continous and follows the kernel address region, but not physically -- physically, it is at the very far end of memory.
Unfortunately, fixing this bug now caused any unused memory in the  FreeLDR-mapped region of 6MB to appear...well...unused. This would normally be a good thing, except ReactOS started crashing.
We fixed it by applying the Glorious Hack. See freelist.c:359.

svn path=/trunk/; revision=32369