* docs/multiboot.h: Replace with include/multiboot.h from GRUB 2 Bazaar
trunk.
* docs/kernel.c (cmain): Update name references for new multiboot.h
header.
* docs/boot.S (ASM): Rename to ...
(ASM_FILE): ... this.
* docs/multiboot.h: Check for `ASM_FILE' instead of `ASM'.
* docs/multiboot.h (EXT_C, STACK_SIZE): Moved from here ...
* docs/boot.S (EXT_C, STACK_SIZE): ... to here.