Use Winapi on both cygwin and mingw32 to share more code between both.

grub-core/disk/geli.c

@@ -210,7 +210,7 @@ make_uuid (const struct grub_geli_phdr *header,
 char *
 grub_util_get_geli_uuid (const char *dev)
 {
-  int fd = open (dev, O_RDONLY);
+  grub_util_fd_t fd = grub_util_fd_open (dev, O_RDONLY);
   grub_uint64_t s;
   unsigned log_secsize;
   grub_uint8_t hdr[512];
@@ -218,7 +218,7 @@ grub_util_get_geli_uuid (const char *dev)
   char *uuid; 
   gcry_err_code_t err;
 
-  if (fd < 0)
+  if (!GRUB_UTIL_FD_IS_VALID (fd))
     return NULL;
 
   s = grub_util_get_fd_size (fd, dev, &log_secsize);