* kern/emu/hostdisk.c (convert_system_partition_to_system_disk):
Support 'p' as partition separator on kernel of FreeBSD (used
with GPT labels).
(grub_util_biosdisk_get_grub_dev): Likewise.
(grub_device_mapper_supported): New function.
* include/grub/emu/misc.h (grub_device_mapper_supported): Add
prototype.
* kern/emu/hostdisk.c (find_partition_start): Check whether
device-mapper is supported before trying to use it.
* util/deviceiter.c (grub_util_iterate_devices): Likewise.
