* configure.ac: Change host_os to cygwin for mingw.
(asprintf): New check for function.
* include/grub/symbol.h: Replace #ifndef __CYGWIN__ with
#if ! defined (__CYGWIN__) && ! defined (__MINGW32__).
* include/grub/util/misc.h: #include <config.h> and <grub/types.h>,
declear asprintf if HAVE_ASPRINTF is not set, declear fseeko, ftello,
sync, sleep and grub_util_get_disk_size for mingw.
* util/biosdisk.c (grub_util_biosdisk_open): Use grub_util_get_disk_size
to get size in mingw.
(open_device): Use flag O_BINARY if it's defined.
(find_root_device): Add dummy code for mingw.
* util/grub-mkdevicemap.c (get_floppy_disk_name): Return 0 for mingw.
(get_ide_disk_name): Return //./PHYSICALDRIVE%d for mingw.
(get_scsi_disk_name): Return 0 for mingw.
* util/hostfs.c: #include <grub/util/misc.h>.
(grub_hostfs_open): Use "rb" flag to open file, use
grub_util_get_disk_size to get disk size for mingw.
* util/misc.c: #include <windows.h> and <winioctl.h> in mingw.
(asprintf): New function if HAVE_ASPRINTF is not set.
(sync): New function for mingw.
(sleep): Likewise.
(grub_util_get_disk_size): Likewise.
