Tweak squashfs for low-memory systems
Tweak squashfs for low-memory systems

On low-memory systems (below 2GB of RAM), limit unsquashfs to a single
CPU and to 10% of the RAM for its fragment size.

Closes #2382

Signed-off-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>

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