[Patch,Fortran] PR 40580 - add -fcheck=pointer for some actual argument checks

[Craig Powers]

Tobias Burnus wrote:

> PS: The patch contains two other small changes; one to *def is trivial
> and one to *.texi brings the words closer to the standard and describes
> better what is actually done (e.g. copy-in/out is not really call by
> reference, though the effect is [almost] the same).

> +call-by-value by default while Fortran behaves usually similar to
> +call-by-reference" Furthermore, strings and pointers are handled
> +differently.

One trivial typo: there's a '"' where there should be a '.'.

One wording quibble: I think I would make it,
...while Fortran behavior is usually...