* stage2/builtins.c [GRUB_UTIL] (dump_func): New function.
[GRUB_UTIL] (builtin_dump): New variable.
(builtin_table) [GRUB_UTIL]: Added a pointer to BUILTIN_DUMP.
* util/grub-install.in: Make sure that GRUB reads the same
images as the host operating system by comparing the result of
running the command "dump" with the contents of the OS file.