[llvm] [MC][Wasm] Emit useful error message when encountering common symbols (PR #179586)

[Derek Schuff via llvm-commits]

dschuff wrote:

FWIW, I still think it would probably be good to eventually support Common symbols in some form.
There's plenty of old C code still around (including in the LLVM test suite), and IIUC some form might also
be needed to support FORTRAN.

https://github.com/llvm/llvm-project/pull/179586