Add support for Exceptions Handling proposal

[MaxDesiatov]

See proposal overview for more details.

Resolves #224.

[MaxDesiatov]

M1 MacBook Air with containerized Ubuntu Noble:

Benchmark                                        main (ms)      eh (ms)   delta%
     --------------------------------------------------------------------------------
     aead_chacha20poly1305.wasm.csv                      401.8        395.6     -1.6%
     aead_chacha20poly13052.wasm.csv                     848.0        836.7     -1.3%
     aead_xchacha20poly1305.wasm.csv                     421.1        413.3     -1.9%
     auth.wasm.csv                                       113.6        112.2     -1.2%
     auth2.wasm.csv                                       19.6         18.8     -3.9%
     auth3.wasm.csv                                       24.6         23.7     -3.7%
     auth6.wasm.csv                                       22.5         21.3     -5.3%
     box.wasm.csv                                       1335.1       1308.0     -2.0%
     box2.wasm.csv                                      1339.8       1316.6     -1.7%
     box_easy.wasm.csv                                  2605.7       2593.9     -0.5%

● CoreMark (higher is better):

  ┌───────┬─────────┬───────────┬───────┐
  │       │  main   │ eh-branch │ Delta │
  ├───────┼─────────┼───────────┼───────┤
  │ Score │ 2125.04 │ 2140.33   │ +0.7% │
  └───────┴─────────┴───────────┴───────┘

  WishYouWereFast / hyperfine (lower is better):

  ┌────────────────────────┬───────────┬─────────┬───────┐
  │       Benchmark        │ main (ms) │ eh (ms) │ Delta │
  ├────────────────────────┼───────────┼─────────┼───────┤
  │ aead_chacha20poly1305  │ 401.8     │ 395.6   │ -1.6% │
  ├────────────────────────┼───────────┼─────────┼───────┤
  │ aead_chacha20poly13052 │ 848.0     │ 836.7   │ -1.3% │
  ├────────────────────────┼───────────┼─────────┼───────┤
  │ aead_xchacha20poly1305 │ 421.1     │ 413.3   │ -1.9% │
  ├────────────────────────┼───────────┼─────────┼───────┤
  │ auth                   │ 113.6     │ 112.2   │ -1.2% │
  ├────────────────────────┼───────────┼─────────┼───────┤
  │ auth2                  │ 19.6      │ 18.8    │ -3.9% │
  ├────────────────────────┼───────────┼─────────┼───────┤
  │ auth3                  │ 24.6      │ 23.7    │ -3.7% │
  ├────────────────────────┼───────────┼─────────┼───────┤
  │ auth6                  │ 22.5      │ 21.3    │ -5.3% │
  ├────────────────────────┼───────────┼─────────┼───────┤
  │ box                    │ 1335.1    │ 1308.0  │ -2.0% │
  ├────────────────────────┼───────────┼─────────┼───────┤
  │ box2                   │ 1339.8    │ 1316.6  │ -1.7% │
  ├────────────────────────┼───────────┼─────────┼───────┤
  │ box_easy               │ 2605.7    │ 2593.9  │ -0.5% │
  └────────────────────────┴───────────┴─────────┴───────┘

[MaxDesiatov]

Verified end-to-end with

clang version 21.1.4-wasi-sdk (https://github.com/llvm/llvm-project 222fc11f2b8f25f6a0f4976272ef1bb7bf49521d) 

and an invocation like this

clang --target=wasm32-wasi \
    -fwasm-exceptions -mllvm -wasm-enable-sjlj \
    -mllvm -wasm-use-legacy-eh=false \
    -O1 -lsetjmp

simple setjmp/longjmp examples run same on Linux and WASI. Unfortunately, WASI SDK doesn't build libc++ with exceptions enabled to verify those.

[MaxDesiatov]

I temporarily pushed ec7f3a1 for detailed library benchmarks on macOS M1 MBA.

On macOS CoreMark main is 2288.147742, and this branch is 2293.072187: 0.2% difference

[kateinoigakukun]

I'll take a dedicated time to review but I don't think I can make it this week 🙇