Some DWARF5 backports for 2.35.2

[Mark Wielaard]

Hi,

I prepared some backports for the binutils-2_35-branch:

[PATCH 1/9] binutils: Handle DWARF5 DW_FORM_ref_addr and
[PATCH 2/9] Sync libiberty and include with GCC for get_DW_UT_name.
[PATCH 3/9] readelf: Show Unit Type for DWARF5
[PATCH 4/9] binutils: dwarf.c handle DWARF5 DW_LLE_start_end and
[PATCH 5/9] readelf: Fix output of rnglists section
[PATCH 6/9] gas: Reuse the input file entry in the file table
[PATCH 7/9] Work around problem in DWARF decoding library which can
[PATCH 8/9] Fix the decoding of DW_FORM_ref_addr DWARF attribute.
[PATCH 9/9] Accept the DW_FORM_ref8 type when parsing DWARF types.

It would be nice if they could go into a future 2.35.2 release
which we can then recommend to be used alongside GCC11 when that
defaults to DWARF5. Except for the gas change they are not strictly
needed to make GCC produce valid DWARF5. But they make working with
DWARF5 much easier in projects that use binutils readelf in their
testsuite.

Most of them applied without any trouble. I did squash the commits
for fixing PR26778 together because that took a couple of tries
and this way it is easier to see what the final change looks like.

I did make sure that every individual commit passes all testsuites
on x86_64-pc-linux-gnu.

They are also in the following git tree if that makes review easier:
https://code.wildebeest.org/git/user/mjw/binutils-gdb/log/?h=binutils-2_35-branch-dwarf

OK, to push these to the binutils-2_35-branch?

Thanks,

Mark