[gdb/symtab] Dump qualified name of cooked_index_entry

When doing "maint print objfiles" for the exec of test-case
gdb.dwarf2/pr13961.exp, we get:
...
    [25] ((cooked_index_entry *) 0x37b25d0)
    name:       foo
    canonical:  foo
    DWARF tag:  DW_TAG_class_type
    flags:      0x0 []
    DIE offset: 0x2a
    parent:     ((cooked_index_entry *) 0)

    [26] ((cooked_index_entry *) 0x37b2630)
    name:       foo
    canonical:  foo
    DWARF tag:  DW_TAG_class_type
    flags:      0x0 []
    DIE offset: 0x25
    parent:     ((cooked_index_entry *) 0x37b25d0) [foo]
...

By following the parent links in the text, we can conclude that the qualified
name of DIE 0x25 is foo::foo (which is incorrect, that's PR symtab/30739).

But it's not evident, and also hard to verify in a test-case.

Add dumping of the qualified name, such that we have:
...
    [25] ((cooked_index_entry *) 0x333b5d0)
    name:       foo
    canonical:  foo
    qualified:  foo
    DWARF tag:  DW_TAG_class_type
    flags:      0x0 []
    DIE offset: 0x2a
    parent:     ((cooked_index_entry *) 0)

    [26] ((cooked_index_entry *) 0x333b630)
    name:       foo
    canonical:  foo
    qualified:  foo::foo
    DWARF tag:  DW_TAG_class_type
    flags:      0x0 []
    DIE offset: 0x25
    parent:     ((cooked_index_entry *) 0x333b5d0) [foo]
...

Tested on x86_64-linux.

Approved-By: Tom Tromey <[email protected]>

Author: vries

gdb/dwarf2/cooked-index.c

@@ -565,6 +565,8 @@ cooked_index::get_main () const
 void
 cooked_index::dump (gdbarch *arch) const
 {
+  auto_obstack temp_storage;
+
   /* Ensure the index is done building.  */
   this->wait ();
 
@@ -579,6 +581,7 @@ cooked_index::dump (gdbarch *arch) const
       gdb_printf ("    [%zu] ((cooked_index_entry *) %p)\n", i++, entry);
       gdb_printf ("    name:       %s\n", entry->name);
       gdb_printf ("    canonical:  %s\n", entry->canonical);
+      gdb_printf ("    qualified:  %s\n", entry->full_name (&temp_storage, false));
       gdb_printf ("    DWARF tag:  %s\n", dwarf_tag_name (entry->tag));
       gdb_printf ("    flags:      %s\n", to_string (entry->flags).c_str ());
       gdb_printf ("    DIE offset: 0x%" PRIx64 "\n",