[lld] [llvm] [lld][WebAssembly] Report undefined symbols by default -shared/-pie builds (PR #75242)

[Sam Clegg via llvm-commits]

sbc100 wrote:

I've updated the PR description to give more detail.   This change doesn't actually add a new symbol kind anywhere except internally within the linker.   All we are doing is making use of existing information which was previously being ignored by the linker.

https://github.com/llvm/llvm-project/pull/75242