board/qemu: Generate sdcard.img with post-image

In order to test AimeeOS A/B filesystem updates, we need a full disk
image just like the Raspberry Pi variant has.

board/qemu/post-image.sh

@@ -0,0 +1,22 @@
+#!/bin/sh
+
+set -e
+
+BOARD_DIR=$(dirname "$0")
+GRUBENV="${BINARIES_DIR}"/efi-part/EFI/BOOT/grubenv
+
+genimage_tmp=$(mktemp -d)
+trap 'rm -rf "${genimage_tmp}"' EXIT
+
+mkdir -p  "${genimage_tmp}"/rootfs "${genimage_tmp}"/tmp
+
+grub-editenv "${GRUBENV}" set default=0
+grub-editenv "${GRUBENV}" set timeout=3
+
+cd "${BINARIES_DIR}"
+genimage \
+	--rootpath "${genimage_tmp}/rootfs" \
+	--tmppath "${genimage_tmp}/tmp" \
+	--inputpath "${BINARIES_DIR}" \
+	--outputpath "${BINARIES_DIR}" \
+	--config "${BOARD_DIR}"/genimage.cfg