We don't have a new bashate release yet, but this fixes some minor
issues when used with bashate trunk.
The only two things triggered are stricter checking of assignment in
local declartions (catches quotes) and one instance of evaluating
arithmetic result in tools/xen/functions.
Therefore, hopefully, this change has no effect!
Change-Id: I3fd5d55236e90c2f2c25243af87adaf0c1b763e2