Add -fno-fortran-main driver option

Author: mjklemm

clang/include/clang/Driver/Options.td

@@ -6354,6 +6354,10 @@ def J : JoinedOrSeparate<["-"], "J">,
   Group<gfortran_Group>,
   Alias<module_dir>;
 
+def no_fortran_main : Flag<["-"], "fno-fortran-main">,
+  Visibility<[FlangOption]>, Group<f_Group>,
+  HelpText<"Don't link in Fortran main">;
+
 //===----------------------------------------------------------------------===//
 // FC1 Options
 //===----------------------------------------------------------------------===//