Ensure GRUB_KERNEL_MACHINE_DATA_END is always consistent with the
rest of GRUB, and breakage doesn't happen if its value were modified.
* include/grub/i386/pc/kernel.h (GRUB_KERNEL_MACHINE_RAW_SIZE):
Redefine as an offset from `GRUB_KERNEL_MACHINE_DATA_END' instead of
a constant (same value).
* kern/i386/pc/startup.S: Replace hardcoded `0x50' with
`GRUB_KERNEL_MACHINE_DATA_END' (same value).
c5e3cfba13