LLVM uses too much memory when compiling an emscripten test with stackmaps enabled

[losfair]

Describe the bug

When running the emscripten test test_indirectbr_many, memory usage goes up by >10GB and testing is not able to complete both on CI and on my computer.

Steps to reproduce

1. Remove the ignore attribute on fn test_test_indirectbr_many.
2. Run: cargo test --manifest-path lib/emscripten-tests/Cargo.toml --release --features llvm -- --test-threads=1 .
3. Watch the memory usage.

Expected behavior

Test successfully finishes.

Actual behavior

Memory usage keeps increasing until crash.

[Hywan]

Solved with the rewrite.