Adding a patch for grub, so livecds with grub can still boot with buggy bioses,

as those of Acer 292LMi or Airis N990. This allows booting the NixOS ISO releases.
I made it optional, not included by default. I don't think it would harm at all enabling
it always - let it be decided on forum.

svn path=/nixpkgs/trunk/; revision=16341

pkgs/tools/misc/grub/buggybios.patch

@@ -0,0 +1,11 @@
+Taken from: http://savannah.gnu.org/bugs/?func=detailitem&item_id=10433
+--- grub-0.95.orig/stage2/bios.c 2004-03-27 17:34:04.000000000 +0100
++++ grub-0.95/stage2/bios.c 2005-03-02 01:02:29.192582200 +0100
+@@ -147,6 +147,7 @@
+   grub_memset (&cdrp, 0, sizeof (cdrp));
+   cdrp.size = sizeof (cdrp) - sizeof (cdrp.dummy);
+   err = biosdisk_int13_extensions (0x4B01, drive, &cdrp);
++  err = 0; /* really ugly hack to circumvent faulty BIOS versions like Acer 292LMi */
+   if (! err && cdrp.drive_no == drive)
+     {
+        if ((cdrp.media_type & 0x0F) == 0)