The correct upstream bug is https://sourceware.org/bugzilla/show_bug.cgi?id=21792 which has been resolved for the 0.170 release:
Although it isn't full DWARF5 support all DWARF5 tags and attributes are recognized in 0.170. From the NEWS file:
Version 0.170
libdw: Added new DWARF5 attribute, tag, character encoding, language code,
calling convention, defaulted member function and macro constants
to dwarf.h.
New functions dwarf_default_lower_bound and dwarf_line_file.
dwarf_peel_type now handles DWARF5 immutable, packed and shared tags.
dwarf_getmacros now handles DWARF5 .debug_macro sections.
And the above example now shows:
[ 7e1] namespace
name (strp) "__cxx11"
decl_file (data1) 1
decl_line (data2) 2214
export_symbols (flag_present) yes
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHEA-2018:0891