Support cabal install glean

[simonmar]

Tracking progress towards cabal install glean so that others can test it

The current state is on these branches:

• hsthrift: https://github.com/simonmar/hsthrift/tree/hackage-0.2.0.0
• Glean: https://github.com/simonmar/Glean/tree/hackage

Tested on:

• Ubuntu 24.04, x86_64, gcc

Candidate Hackage packages:

• https://hackage.haskell.org/package/folly-clib-20250702.629/candidate
• https://hackage.haskell.org/package/fb-util-0.2.0.0/candidate
• https://hackage.haskell.org/package/thrift-compiler-0.2.0.0/candidate
• https://hackage.haskell.org/package/thrift-haxl-0.2.0.0/candidate
• https://hackage.haskell.org/package/thrift-http-0.2.0.0/candidate
• https://hackage.haskell.org/package/glean-0.1.0.0/candidate

These can be downloaded and tested locally.

PRs that still need merging:

• Changes for Hackage release 0.2.0.0 hsthrift#158
• new-hs-indexer PRs (strictly speaking these aren't blocking a Hackage release, but it would be nice to get them into the first release): [new-hs-indexer #16] Index type signatures #550 [new-hs-indexer #17] Index instance declarations and class defaults #551 [new-hs-indexer #18] Refactor: switch to OverloadedRecordDot #552

[simonmar]

done!