Hi All,

I request you all to please review this patch. Below are the details.

Problem Description:
    Currently, GDB rejects the (die) reference form while it accepts exprloc
    form. It is allowed in DWARF standard. "Table 7.5: Attribute encodings"
    in DWARF5 standard. Flang compiler assigns (die) reference to
    DW_AT_associated and DW_AT_allocated for some cases. 
Resolution:
    Now ' set_die_type' Is modified to accept reference form as well.
This change will not impact testsuite for gfortran, and will fix failures for
Flang compiler with existing testsuite.

    gdb/ChangeLog

            * dwarf2/read.c (set_die_type): Allow reference form for
            DW_AT_associated and DW_AT_allocated attributes.

Please let me know your valuable comments.

Regards,
Alok