lxc-to-lxd: Handle linux32 and linux64 arch personalities
lxc-to-lxd: Handle linux32 and linux64 arch personalities

If lxc.arch is linux32 or linux64, the architecture ID cannot be
determined as multiple architectures have the linux32 or linux64
personality. In this case, assume the native architecture.

This fixes #10865.

Signed-off-by: Thomas Hipp <5f82c492b3b00e427412d216ce820707a10c51ce@canonical.com>

lxc/lxd,lxc/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,lxc/lxd,lxc/lxd,stgraber/lxd