Remove osloader.c and replace with a prep_segment() that uses userptr_t

and get_memmap() in image/segment.c

src/arch/i386/image/nbi.c

@@ -2,7 +2,6 @@
 #include "memsizes.h"
 #include "realmode.h"
 #include "gateA20.h"
-#include "osloader.h"
 #include "etherboot.h"
 #include "errno.h"