qemu-vm: create erofs with hard-dereference flag (#395494)

Changed files
+1
nixos
modules
virtualisation
+1
nixos/modules/virtualisation/qemu-vm.nix
···
-L ${nixStoreFilesystemLabel} \
-U eb176051-bd15-49b7-9e6b-462e0b467019 \
-T 0 \
+
--hard-dereference \
--tar=f \
"$TMPDIR"/store.img