The main program in D is _Dmain (demangled as 'D main') not C 'main'.
So the logical entry point of the program should be set accordingly.

2014-01-09  Iain Buclaw  <ibuclaw@gdcproject.org>

        * d-lang.h (d_main_name): Add declaration.
        * d-lang.c (d_main_name): New function.
        * symtab.c (find_main_name): Add call to d_main_name.

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