[llvm] [llvm-ar] Introduce -wholearchive linker hint. (PR #195834)

[via llvm-commits]

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@@ -382,6 +382,11 @@ class LLVM_ABI Archive : public Binary {
     return std::move(ThinBuffers);
   }
 
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zackc6 wrote:

Suggest 
``` static constexpr StringLiteral kWholeArchiveString = "-wholearchive"; ```
and replace all hardcoded string


https://github.com/llvm/llvm-project/pull/195834