[patch, fortran] Implement IS_CONTINUOUS intrinsic

[Steve Kargl]

On Sun, Jan 06, 2019 at 11:04:12PM +0100, Thomas Koenig wrote:
> 
> the attached patch builds on a long history:  Tobias Burnus created
> an original version in 2012. Harald Anlauf recently picked it up,
> (see https://gcc.gnu.org/ml/fortran/2019-01/msg00012.html).
> polished it and made it ready for gcc-9.  This already worked
> quite well.  I added a bit of compile-time simplification (where we can
> prove an array is not contiguous). The original library function version
> was by Harald, but I replaced that with something simpler; also the
> code would have pushed the limits for contributions without
> (yet) a copyright assignment in place.
> 
> Later, we can also use the gfc_is_not_contiguous to reject
> obvious errors when assigning to contiguous pointers or
> arguments.
> 
> Regression-tested on x86_64-pc-linux-gnu. OK for trunk?
> 

OK.

Thanks Thomas, Harald, and Tobias!

-- 
Steve