[clang] [Driver][DragonFly] Fixes for linker path and command-line option handling (PR #69095)

[Fangrui Song via cfe-commits]

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@@ -56,7 +56,9 @@ void dragonfly::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                                      const InputInfoList &Inputs,
                                      const ArgList &Args,
                                      const char *LinkingOutput) const {
-  const Driver &D = getToolChain().getDriver();
+  const toolchains::DragonFly &ToolChain =
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MaskRay wrote:

`const auto &` as `static_cast` makes the type clear

https://github.com/llvm/llvm-project/pull/69095