[DOC] Fix copyright statements of manuals

[Jerry DeLisle]

Ralf Wildenhues wrote:
---snip ---
> 
> gcc/fortran/ChangeLog:
> 2008-07-20  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
> 
> 	* gfc-internals.texi: Update to GFDL 1.2.  Do not list GPL as
> 	Invariant Section.
> 	* gfortran.texi: Likewise.
> 	* intrinsic.texi: Do not list GPL as Invariant Section.
> 	* invoke.texi: Likewise.  Update copyright years.
> 

Fortran parts are OK.

Jerry