Pmbootstrap: Root partition not resized automatically on non-x86_64 Qemu

[PureTryOut]

Even though pmbootstrap reports otherwise, --image-size <whatever> doesn't actually do anything when running Qemu on a non-x86_64 architecture (in my testing, armhf).

If I manually resize the image using truncate +1G qemu-vexpress.img, pmbootstrap does however complain when not setting --image-size to the correct value.

ERROR: The system image size must be 3072M or greater

But when booting the image, the root partition doesn't get resized to use up all the new space.

[drebrez]

The --image-size argument works as expected. The real issue is that the partition is not resized.
This is due the way we use to detect it, see here.
In the qemu-vexpress the root partition is /dev/mmcblk0p2, but if we change the resize function to detect that one, we will also start resizing the device partitions or the partitions in the actual sd-cards.

I see some possible solutions to force the partition resize:

1. using a deviceinfo variable (ex: deviceinfo_initfs_force_partition_resize="true")
2. using a cmdline parameter (ex: PMOS_FORCE_PARTITION_RESIZE)
3. hardcode something like if devicename starts with qemu then resize

@ollieparanoid what you think about it?

[ollieparanoid]

I would prefer the 2nd option, because we only need this in the initramfs and we do it the same way with the logging already.