[NTOS]: MiRosTakeOverPebTebRanges now creates a small ~1MB ARM3 memory range on top...

[NTOS]: Knowing if this change causes issues will help later in determining regressions due to TEB/PEBs mapped as VADs by ARM3, and regressions simply due to the change in VA layout.
[NTOS]: When implemented, the VAD mapping for PEB/TEB will only use that ~1MB, which yes, will limit ReactOS processes to each have only 256 threads. That is obviously a temporary limitation, one I doubt we'll even hit, but I'm putting it out here so you know.

svn path=/trunk/; revision=48176