* util/grub-mkconfig_lib.in (gettext_quoted): Add clarifying

comment.  Add an extra layer of quotation, requiring the output of
this function to be used in a printf format string.
(gettext_printf): New function.
* util/grub.d/10_hurd.in: Use gettext_printf where appropriate.
Extract translatable strings from here-documents and use a temporary
variable instead, so that xgettext can find them.
* util/grub.d/10_kfreebsd.in: Likewise.
* util/grub.d/10_linux.in: Likewise.
* util/grub.d/20_linux_xen.in: Likewise.

* po/grub.d.sed: New file.
* po/Makefile.in.in ($(DOMAIN).pot-update): Extract gettext_printf
arguments.  Set c-format flags on all strings extracted from
util/grub.d/ (xgettext refuses to include these itself for strings
it extracted from a shell file, but these really are c-format).

util/grub.d/10_linux.in

@@ -94,13 +94,15 @@ EOF
     prepare_boot_cache="$(prepare_grub_to_access_device ${GRUB_DEVICE_BOOT} | sed -e "s/^/\t/")"
   fi
   printf '%s\n' "${prepare_boot_cache}"
+  message="$(gettext_printf "Loading Linux %s ..." ${version})"
   cat << EOF
-	echo	'$(printf "$(gettext_quoted "Loading Linux %s ...")" ${version})'
+	echo	'$message'
 	linux	${rel_dirname}/${basename} root=${linux_root_device_thisversion} ro ${args}
 EOF
   if test -n "${initrd}" ; then
+    message="$(gettext_printf "Loading initial ramdisk ...")"
     cat << EOF
-	echo	'$(gettext_quoted "Loading initial ramdisk ...")'
+	echo	'$message'
 	initrd	${rel_dirname}/${initrd}
 EOF
   fi