vfs: pre-map (to the 'zero page') AnonymousMemoryMap, fix some logic bugs in MemoryMappedFile::trap.
posix: /dev/fb - no ioctls yet, and still very much a work in progress.
winman: use /dev/fb & mmap for the framebuffer. Things are getting closer to working, though winman aborts for some reason.
posix: handle errors in file mapping in mmap, better logging too.