Fix canonicalize_file_name clash.

canonicalize_file_name clashed with gnulib function. Additionally
it was declared in 2 places: emu/misc.h and util/misc.h. Added
grub_ prefix and removed second declaration.

grub-core/kern/emu/hostdisk.c

@@ -184,7 +184,7 @@ grub_hostdisk_os_dev_to_grub_drive (const char *os_disk, int add)
   unsigned int i;
   char *canon;
 
-  canon = canonicalize_file_name (os_disk);
+  canon = grub_canonicalize_file_name (os_disk);
   if (!canon)
     canon = xstrdup (os_disk);
 
@@ -535,7 +535,7 @@ read_device_map (const char *dev_map)
       /* On Linux, the devfs uses symbolic links horribly, and that
 	 confuses the interface very much, so use realpath to expand
 	 symbolic links.  */
-      map[drive].device = canonicalize_file_name (p);
+      map[drive].device = grub_canonicalize_file_name (p);
       if (! map[drive].device)
 	map[drive].device = xstrdup (p);