[clang] [flang][driver] Don't use -whole-archive on Darwin (PR #75393)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> > LGTM. Worked fine on my machine.
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> > NOTE: tested by replacing `CommonArgs.cpp` in main, to avoid conflicts.
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> Thanks for checking and apologies for the merge conflict - I thought that I was up to date :( I've just rebased and force-pushed. 
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> I will be landing this today if there are no further comments 🙏🏻 

This patch seems to hide the original problem of the compiler not erroring out when multiple definitions of main happen.  T think we should rather inject the proper linker equivalent of --whole-archive on Darwin, too.

I'd be OK to land this patch for now, if we agree to have a follow up PR to (re-)instantiate the error handling also for Darwin.

https://github.com/llvm/llvm-project/pull/75393