746f09b427
added --enable-repeat-speedups with default to disabled. Reconfigure/recompile and the speedup code will be #ifdef'd out for now. It manifested as junk written to the VGA screen while booting/running Windows. Also made some more mods to the main cpu loop. Moved the handling of EXT/errorno outside the main loop, much like the extra EIP/ESP commits were moved, for a little better performance. I changed the fetch_ptr/bytesleft method of fetching to a slightly different model, which calculates a window for which EIP will be valid (land on the current page), and a bias which when applied to EIP will be from 0..upper_page_limit. Speed is about the same for either method, but a pseudo-op/threaded-interpreter will plug in better with this and be faster.