* util/grub-mkconfig.in: Stop setting GRUB_VIDEO_BACKEND. Make it

available as a user override instead.  Replace the gfxterm backend
check with a check that ${GRUB_PREFIX}/video.lst is non-empty.
* util/grub.d/00_header.in (load_video): New generated function.
Call it before loading gfxterm rather than loading
${GRUB_VIDEO_BACKEND}.
* util/grub.d/10_linux.in (linux_entry): Call load_video.
* util/grub.d/30_os-prober.in (osx_entry): Likewise.
* docs/grub.texi (Simple configuration): Document
GRUB_VIDEO_BACKEND.

util/grub-mkconfig.in

@@ -181,10 +181,7 @@ for x in ${GRUB_TERMINAL_OUTPUT}; do
 	    GRUB_TERMINAL_OUTPUT=
 	    break;
 	fi
-        # FIXME: this should do something smarter than just loading first
-        # video backend.
-	GRUB_VIDEO_BACKEND=$(head -n 1 ${GRUB_PREFIX}/video.lst || true)
-	if [ -z "${GRUB_VIDEO_BACKEND}" ] ; then
+	if [ ! -s "${GRUB_PREFIX}/video.lst" ] ; then
 	    if [ "x$termoutdefault" != "x1" ]; then
 		echo "No suitable backend could be found for gfxterm." >&2 ; exit 1
 	    fi
@@ -242,7 +239,6 @@ export GRUB_DEVICE \
   GRUB_FS \
   GRUB_FONT_PATH \
   GRUB_PRELOAD_MODULES \
-  GRUB_VIDEO_BACKEND \
   GRUB_PREFIX
 
 # These are optional, user-defined variables.
@@ -265,6 +261,7 @@ export GRUB_DEFAULT \
   GRUB_DISABLE_LINUX_UUID \
   GRUB_DISABLE_LINUX_RECOVERY \
   GRUB_DISABLE_NETBSD_RECOVERY \
+  GRUB_VIDEO_BACKEND \
   GRUB_GFXMODE \
   GRUB_BACKGROUND \
   GRUB_THEME \