[llvm] add: hidden option to disable slow wasm pass (PR #67715)

[Sam Clegg via llvm-commits]

sbc100 wrote:

What happens if the program contains irreducible control flow?  Will the compiler crash or fail somewhere further down the line?

@sunfishcode @dschuff @kripken 

https://github.com/llvm/llvm-project/pull/67715