[flang-commits] [flang] [flang][debug] set DW_AT_main_subprogram for fortran main function (PR #111350)

[Tom Eccles via flang-commits]

tblah wrote:

For
```
program example
end program
```

Both before and after this patch using gdb 15.0.50. 
```
(gdb) info main
example
```

I'm not sure how gdb found the right name before this patch. I can't see the `DW_AT_main_subprogram` attribute in `objdump -g` output before this patch and do after.

https://github.com/llvm/llvm-project/pull/111350