Define grub_util_is_directory/regular/special_file and

use OS-dependent versions rather than to rely on stat().

include/grub/emu/hostfile.h

@@ -24,6 +24,13 @@
 #include <sys/types.h>
 #include <grub/osdep/hostfile.h>
 
+int
+grub_util_is_directory (const char *path);
+int
+grub_util_is_special_file (const char *path);
+int
+grub_util_is_regular (const char *path);
+
 int
 grub_util_fd_seek (grub_util_fd_t fd, grub_uint64_t off);
 ssize_t