[clang] [flang] [flang][Driver] Support -gsplit-dwarf. (PR #160540)

[Tom Eccles via cfe-commits]

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@@ -131,20 +135,57 @@ void Flang::addOtherOptions(const ArgList &Args, ArgStringList &CmdArgs) const {
                    options::OPT_finstrument_functions});
 
   llvm::codegenoptions::DebugInfoKind DebugInfoKind;
+  bool hasDwarfNArg = getDwarfNArg(Args) != nullptr;
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tblah wrote:

Not strictly necessary no because nullptr will be 0==false, but I think this is easier to understand at a glance.

https://github.com/llvm/llvm-project/pull/160540