This includes an upstream fix to the hcldec.Variables function that fixes
its behavior when dealing with specs that contain DefaultSpec, and other
similar wrapper specs.
This includes a number of upstream fixes, but in particular fixes a race
on evaluating the same splat expression concurrently for multiple separate
EvalContexts.
This is largely minor bugfixes for issues found since we last updated the
vendoring. There are some new features here that Terraform is not yet
using and thus present little risk.
In particular this includes the HCL-JSON spec change where arrays can now
be used at any level in a block label structure, to allow for preserving
the relative order of blocks.