[PATCH, fortran] Interoperability with C int128_t types

[Tobias Burnus]

Sa Liu wrote:
>>   if (gfc_notify_std (std_for_isocbinding_symbol (s),
>>                             "Extension: '%s' symbol in ISO_C_BINDING
>>  intrinsic module at %C",
>>                             name) == FAILURE)
>>     return;
>>     
> I don't think we should issue an error here, when generating the 
> isocbinding symbols. Even if no extension types are used in program, the 
> compiler will go through the type definitions and check their standards. 
> In stead, we could just ignore the extension types and don't generate 
> symbols for them if -std=f2003
I am in favour of this: This allows for the user-defined symbol 
int128_t; otherwise there pathological cases where we  gfortran 
-std=f2003 rejects valid programs. (Ok, as they are very pathologically, 
given an error is an equally good choice.)

Tobias