[llvm] [WebAssembly] Allocate MCSymbolWasm data on MCContext. (PR #85866)

[Derek Schuff via llvm-commits]

https://github.com/dschuff approved this pull request.

Overall I like this change a lot; the MCContext is really the more "correct" place to store these strings, and the previous code was trying (and not quite succeeding) to avoid putting wasm-specific things there, but then had to hack around the fact that the storage lifetimes got awkward.

Regarding who reviews: MCContext is one of those parts of the code where there are many stakeholders, but no real "owner" so it's hard to get things reviewed sometimes. Maybe having me approve this will get someone's attention? :)

https://github.com/llvm/llvm-project/pull/85866