Improve ELFObjectWriter difference across sections diagnostic

[rener]

Summary

While building Firefox with Rustc and LLVM 16 I came across some nw section difference mismatch issues. Without any context it was impossible to find out what the issue was, so let's add some context, like symbol and section for the developer to better understand what is going on.

llvm-16.0.1.src/lib/MC/ELFObjectWriter.cpp

     const MCSection &SecB = SymB.getSection();
     if (&SecB != &FixupSection) {
       Ctx.reportError(Fixup.getLoc(),
-                      "Cannot represent a difference across sections");
+          Twine("symbol '") + SymB.getName() +
+                      "' can not represent a difference across sections: " + SecB.getName());
       return;
     }