[gfortran,patch] add ISO_FORTRAN_ENV intrinsic module

[FX Coudert]

> Updated patch, including testsuite coverage, attached. Regtested on  
> i686-linux. Any new comments anyone? OK for mainline?

I should probably add that part of this patch (matching the new F2003  
USE syntax) is common with my patch "F2003 USE syntax and OpenMP  
module" (http://gcc.gnu.org/ml/gcc-patches/2006-10/msg01539.html).  
So, if you review this one, you've already done half of the job of  
reviewing the other one :)

FX