[lld] [lld][WebAssembly] Fix filename when reporting references to undefined symbols (PR #97444)

[Sam Clegg via llvm-commits]

================
@@ -1,30 +1,34 @@
-# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown %s -o %t1.o
+# RUN: split-file %s %t
----------------
sbc100 wrote:

Yeah its kind of nice!   One downside is that the test files themselves are less independently useful, but thats seems like a minor things compared to the hassle of splitting out secondary files into the `Input/` diretory.

https://github.com/llvm/llvm-project/pull/97444