[fortran,patch] Remove unused gfc_open_intrinsic_module()

[Tobias Burnus]

FX wrote:
>>> A quick grep through the front-end indicates that
>>> gfc_open_intrinsic_module() is never used. Should it have been
>>> removed when module file reading/writing was overhauled?
>> I suspect the answer is "yes”.
> HereÂ’s a patch that removes it. It buils fine.
> OK to commit?

I think that qualifies as obvious: The function is not used, that has 
been confirmed by someone else, and the functionality the function is 
supposed to implement already works.

Thanks for the cleanup!

Tobias