smt2_parser: parse Array sort

[kroening]

• Each commit message has a non-empty body, explaining why the change was made.
• My contribution is formatted in line with CODING_STANDARD.md.
• Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
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[allredj]

This PR failed Diffblue compatibility checks (cbmc commit: 09ad8fe).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/87880341
Status will be re-evaluated on next push.
Please contact @peterschrammel, @thk123, or @allredj for support.

Common spurious failures:

• the cbmc commit has disappeared in the mean time (e.g. in a force-push)
• the author is not in the list of contributors (e.g. first-time contributors).

The incompatibility may have been introduced by an earlier PR. In that case merging this
PR should be avoided unless it fixes the current incompatibility.

[allredj]

Passed Diffblue compatibility checks (cbmc commit: 32b9e2c).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/87880689

[allredj]

This PR failed Diffblue compatibility checks (cbmc commit: 0cf070b).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/87998797
Status will be re-evaluated on next push.
Please contact @peterschrammel, @thk123, or @allredj for support.

Common spurious failures:

• the cbmc commit has disappeared in the mean time (e.g. in a force-push)
• the author is not in the list of contributors (e.g. first-time contributors).

The incompatibility may have been introduced by an earlier PR. In that case merging this
PR should be avoided unless it fixes the current incompatibility.