x86: generalize partition discovery for sysupgrade

Generalize the partition discovery in sysupgrade in order to fix sysupgrade
and config backup/recovery on MMC block devices which use a different naming
scheme compared to mtdblock or sd* devices.

The change also adds the find applet to the ramdisk utilities so that upgrade
code can rely on it.

The commit is based on the initial submission by Russell Senior at
http://patchwork.ozlabs.org/patch/625440/ .

Signed-off-by: Russell Senior <russell@personaltelco.net>
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

x86: use PARTUUID instead explicitly specifying the device by default

This changes the x86 image generation to match x86_64, using the PARTUUID for
the rootfs instead of explicitly configuring the device.

It unbreaks KVM with VirtIO, which uses /dev/vda2 instead of /dev/sda2.

Tested in QEMU/KVM with VirtIO, VirtualBox and VMware.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@44966 3c298f89-4303-0410-b956-a3cf2f4a3e73

x86: fix sysupgrade

Function move_config should be called after or during preinit_mount_root
hook in do_mount_root function. At this state sysupgrade.tgz is not in its
place during that time when do_mount_root is called. Function move_config
is called later so the sysupgrade.tgz stays in root directory to the second
restart when it is unpacked properly.

This patch adds move_config function to preinit_mount_root hook instead
of preinit_main and changes the filename of script to be called before
80_mount_root is called. It will prepare the sysupgrade archive for do_mount_root
within preinit_mount_root hook.

This patch solves ticket #15042 and #14088.

Signed-off-by: Jiri Slachta <slachta@cesnet.cz>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39996 3c298f89-4303-0410-b956-a3cf2f4a3e73