[llvm] Fix warnings while building llvm against emscripten for web assembly (PR #118262)

[Sam Clegg via llvm-commits]

sbc100 wrote:

> @sbc100 Seems reasonable, although I will note that I've focused on building LLVM for bare WASI since I need it to run on both JS-ful and JS-less platforms. As such I've never really used Emscripten much; pure-WASI takes different code paths here.

And were you able to build without disabling shared libraries at the core level like this?   (I assume you are not using any shared libraries in WASI since that is not really a thing yet).

https://github.com/llvm/llvm-project/pull/118262