[Patch, fortran] PR20896 - dummy procedures interfaces

[Paul Thomas]

Dear All,

I have now run out of time to do anything with this patch for some 
considerable number of weeks.  It's a pity because I think that in spite 
of some other brands not swallowing the test case, I think that it is 
correct.

Put simply, an external procedure in an interface can not be identified 
to be either a subroutine or a function, unless it is explicitly typed.  
Thus, an untyped, external symbol is always ambiguous with another 
procedure.  On the other hand, if it is explicitly typed, it is 
ambiguous with another function or another external symbol, typed or 
not.  This paraphrases the standard, does it not, Dominique? As far as I 
can tell, this is what the patch implements.

Anyhow, do with it as you will.

Paul