[patch, committed] Fix some mior things on INQUIRE

This committed as simple and obvious.

The log is self explanatory. No more on this.

Regards,

Jerry
---
commit 3e2c1324fadb1a9e422e83187083d231bbe8dec2 (HEAD -> master, origin/master, 
origin/HEAD)
Author: Jerry DeLisle <[email protected]>
Date:   Mon Apr 6 17:55:21 2026 -0700

     fortran: Fix encoding value when file/unit opened without specifying.

     When a file or unit is connected as a formatted I/O and the OPEN
     statement does not set the ENCODING it is set to DEFAULT.

             PR libfortran/124543

     libgfortran/ChangeLog:

             * io/inquire.c (inquire_via_unit): Change the returned
             encoding value to 'DEFAULT' when not specified in the OPEN
             statement.

     gcc/testsuite/ChangeLog:

             * gfortran.dg/pr124543.f90: Add the dg-options "-O0" to
             reduce testing time. Adjust test for the change above.