fix PR 25045, missing checks on optional dim

[Tobias Schlüter]

Thomas Koenig wrote:
> OK for trunk (and, after a few days, for 4.1) if this passes?
> 
> 	Thomas
> 
> 2006-02-06  Thomas Koenig  <Thomas.Koenig@online.de>
> 
> 	PR fortran/25045
> 	* check.c (dim_check):  Perform all checks if dim is optional.
> 	(gfc_check_minloc_maxloc):  Use dim_check and dim_rank_check
> 	to check dim argument.
> 	(check_reduction):  Likewise.
> 
> 2006-02-06  Thomas Koenig  <Thomas.Koenig@online.de>
> 
> 	PR fortran/25045
> 	* optional_dim.f90:  New test.

This is ok.

Thanks,
- Tobi