* util/grub-emu.c: Include signal.h.
(main_env): New global variable.
(grub_machine_init): Ignore SIGINT. Otherwise grub-emu cannot
catch C-c.
(grub_machine_fini): New function.
(main): Call grub_halt_init and grub_reboot_init before
grub_main, and grub_reboot_fini and grub_halt_fini after it.
Call setjmp with MAIN_ENV to go back afterwards.
Call grub_machine_fini right before return.
* include/grub/util/misc.h: Include setjmp.h.
(main_env): New prototype.