[clang] [Driver][MinGW] Always put libc argument last, even if non-standard (PR #149434)

[Martin Storsjö via cfe-commits]

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@@ -85,11 +85,18 @@ void tools::MinGW::Linker::AddLibGCC(const ArgList &Args,
 
   CmdArgs.push_back("-lmoldname");
   CmdArgs.push_back("-lmingwex");
-  for (auto Lib : Args.getAllArgValues(options::OPT_l))
+  for (auto Lib : Args.getAllArgValues(options::OPT_l)) {
     if (StringRef(Lib).starts_with("msvcr") ||
         StringRef(Lib).starts_with("ucrt") ||
-        StringRef(Lib).starts_with("crtdll"))
+        StringRef(Lib).starts_with("crtdll")) {
+      Lib = (llvm::Twine("-l") + Lib).str();
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mstorsjo wrote:

I'd kinda prefer to declare a new variable instead of reusing `Lib` here. Especially with `Lib` being declared `auto`, its type is not entirely obvious here, so it would feel clearer if we'd declare the new one e.g. explicitly `std::string` here.

https://github.com/llvm/llvm-project/pull/149434