[patch, fortran] Fix character length in constructors

[Thomas Koenig]

Am 20.02.2018 um 08:51 schrieb Janne Blomqvist:

> It's better to use gfc_mpz_get_hwi() instead of mpz_get_si().
> mpz_get_si() returns a long, which is a 32-bit type on win64.
> 
> Otherwise Ok with the spelling fix suggested by Steve.

Committed as r257856.

Thanks to you and Steve for the review and the heads_up about
gfc_mpz_get_hwi.

I also changed the "call abort" to "STOP 1" at the last second
(old habits are hard to break, it seems :-)

Regards

	Thomas