[gdb/symtab] Work around PR gas/29517, dwarf2 case
In commit
1d45d90934b ("[gdb/symtab] Work around PR gas/29517") we added a
workaround for PR gas/29517.
The problem is present in gas version 2.39, and fixed in 2.40, so the
workaround is only active for gas version == 2.39.
However, the problem in gas is only fixed for dwarf version >= 3, which
supports DW_TAG_unspecified_type.
Fix this by also activating the workaround for dwarf version == 2.
Tested on x86_64-linux.
Approved-by: Kevin Buettner <kevinb@redhat.com>
PR symtab/31689
https://sourceware.org/bugzilla/show_bug.cgi?id=31689