[clang] [flang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Andrzej Warzyński via cfe-commits]

https://github.com/banach-space commented:

Thanks for pushing on!

I've made one small suggestion and I also have one more request for the summary. I know that you added links to relevant PRs, but I would still appreciate if the summary (and the commit msg) where self-contained and included the justification for this new flag. You could use the example by @tblah to show where the flag might be needed. Please do keep the links :) 

I think that it would also be helpful to include what could be an alternative to this and that wouldn't require a flag - I think that the only option would be to mimic what Classic Flang does?

I know that it's extra work, but it's also super useful bit of documentation. And I would only rarely try to track the history beyond commit messages (there's just too much otherwise). 

https://github.com/llvm/llvm-project/pull/74139