[llvm] [WebAssemblyLowerEmscriptenEHSjLj] Don't assign import names to generated function declarations (PR #71599)

[Sam Clegg via llvm-commits]

sbc100 wrote:

> Sorry for the delayed reply. Does this work because now those symbols arrive not from JS code but from our C/C++ library code? Then does this work with dynamic linking too?
> 
> Also check the clang-format thing

The reason this now works is that we pass a list of known JS function to the linker, which tells the linker its OK to import them.   So we no longer need to tell the linker in to import them using this method. 

The advantage is that when the list of available JS symbols doesn't include one of these we get a nice error from wasm-ld.

https://github.com/llvm/llvm-project/pull/71599