spdx license list update should keep licenses sorted.

## Expected Behavior
After updating //licenses/spdx/BUILD, all the license_kind definitions should be in alphabetical order by name.

## Actual Behavior
After each run, new items are added in alphabetically ordered chunks. That is ugly.

Implementation question: Do we sort with LC_ALL=C or use unicode "human readable" ordering?

Start with //licenses/spdx/BUILD and inspect how the license_kind definitions are generated or updated. Determine whether alphabetical order should use LC_ALL=C or human-readable Unicode ordering, then verify that the definitions remain globally sorted after an update.

Written by the indexing model from the issue text.