Some easy DWARF5 extensions

[Mark Wielaard <mark at klomp dot org>]

Hi,

The following are all the easy DWARF5 extensions that a compiler might
emit in "non-strict" DWARF mode (when it uses tags, attributes or other
constants from a later version of DWARF).

[PATCH 1/9] libdw: Add DWARF5 attributes.
[PATCH 2/9] libdw: Add new DWARF5 tag constants.
[PATCH 3/9] libdw: Add new DWARF5 character encodings.
[PATCH 4/9] libdw: DWARF5 Add new DW_LANG codes and default lower
[PATCH 5/9] libdw: Add dwarf_default_lower_bound.
[PATCH 6/9] libdw: DWARF5 Add DW_CC_pass_by_reference and
[PATCH 7/9] Handle DWARF5 defaulted member function encodings.
[PATCH 8/9] libdw: Handle DWARF5 immutable, packed and shared in
[PATCH 9/9] libdw: Add DW_MACRO constants and DW_MACRO_GNU

This doesn't include the "hard" parts of handling the new DWARF5
unit headers, forms, expression operations, line tables and the
new debug_names, etc. Some of that work can be found here:
https://code.wildebeest.org/git/user/mjw/elfutils/commit/?h=mjw/DWARF5_UT_FORM
but that is still very much a work in progress.

I believe the above patches however are ready and I would like to include
them in the next release. It has been 3 months since the last one, so it
is time to do a new one soon. It would be nice to at least handle these
easy parts of DWARF5 with elfutils 0.170.

Cheers,

Mark