[PATCH] Fix issues with reading rnglists, especially from dwo files, for DWARF v5

[Tom Tromey]

Caroline> $ clang++ -gdwarf-5 -O0 -gsplit-dwarf pre-order.cpp
Caroline> pre-order-common.cpp -o pre-order

I wonder if the test suite can be run this way.

Caroline> Oh.  Those get used in my next upcoming patch (where I update GDB to
Caroline> handle DWARFv5 .dwp files).  I can either leave them in this patch, or
Caroline> remove them from here and put them in the next one, whichever you
Caroline> prefer.

I think it's better for patches to be reasonably self-contained when
possible.

Also, there were other patches for DWARFv5 on the list in "recent" (this
year) times.  I wonder if those are relevant / related.

Tom