[clang] [Driver] Add option to force undefined symbols during linking in BareMetal toolchain object. (PR #132807)

[Garvit Gupta via cfe-commits]

quic-garvgupt wrote:

`ToolChain::UnwindLibType ToolChain::GetUnwindLibType(
    const ArgList &Args) const {
  if (unwindLibType)
    return *unwindLibType;

  const Arg *A = Args.getLastArg(options::OPT_unwindlib_EQ);
  StringRef LibName = A ? A->getValue() : CLANG_DEFAULT_UNWINDLIB;`
  
 If the --unwindlib flag is not set to empty explicitly, then it takes whatever it set by `CLANG_DEFAULT_UNWINDLIB`. I think, by adding `--unwindlib= ` to the instance which is failing should fix the issue

https://github.com/llvm/llvm-project/pull/132807