[flang] [clang] Revert "[flang][Driver] Let the linker fail on multiple definitions of main()" (PR #74120)

[Michael Klemm via cfe-commits]

mjklemm wrote:

I have opened PR #74139 to provide an alternate solution to this.  Please have a look there.

@tblah Would you mind trying this new option with one application code to see if that will help? 

https://github.com/llvm/llvm-project/pull/74120