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

[Sam Clegg via llvm-commits]

sbc100 wrote:

> cc @sbc100
> 
> Do these changes look reasonable to you now ? I think @whitequark approves. Obviously we might find work arounds here and there but shouldn't we cater specific configs needed by specific systems/platforms ?
> 
> I mean I see different setting based on checks like `if(APPLE)`, `If(MSVC)` etc
> 
> But if that's not the case, whatever workaround is there should be well documented somewhere I guess. I've not had problems building llvm but then I see too warnings to ignore, hence in favour of such a change.

If there are existing build settings that effectively disable shared libraries then we should probably just rely on them.

Are you able to make the build work without this patch using settings like these ones: https://github.com/YoWASP/clang/blob/0e0259397c85ba52b7370f6be0f52ae08ba3f4d5/build.sh#L72-L221

Can you update "web assembly" => "WebAssembly".    Perhaps a better title might be "Disable shared libraries when building with emscripten"

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