[coreboot] filo compile errors

[Jason Wang]

hi all
 it seems there is a variable  are not included in /include/grub/shard.h
which would caused error with main/grub/completions.c UNIQUE_BUF undefined
details are patched.

Index: include/grub/shared.h
===================================================================
--- include/grub/shared.h    (revision 103)
+++ include/grub/shared.h    (working copy)
@@ -55,6 +55,7 @@
 #define COMPLETION_BUFLEN    MAX_CMDLINE

/* The buffer for the unique string.  */
+extern char UNIQUE_BUF[];
 #define UNIQUE_BUFLEN        MAX_CMDLINE

/* The buffer for the menu entries.  */