PR libfortran/95195 - improve runtime error for namelist i/o to unformatted file

[Thomas Koenig]

Hello Harald,

> Without the patch below, an attempted namelist write to an unformatted file -
> which is prohibited by the standard - would generate the following runtime error:
> 
> At line 12 of file pr95195.f90 (unit = 10, file = 'test.dat')
> Fortran runtime error: End of record
> 
> followed by some backtrace.  The patch attempts to generate an error pointing
> the user to the real issue.
> 
> Regtested on x86_64-pc-linux-gnu.
> 
> OK for master?

OK, thanks for the patch!

Regards

	Thomas