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

[Michael Klemm via cfe-commits]

mjklemm wrote:

This WIP for now, as I still have to make the changes for MSVC.  But it's good enough to discuss if this is a viable solution.

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