pushed: Add support for DWARF-based fixed point types

[Joel Brobecker]

> >  $ ./gdb -ex "maint selftest gdb_mpq_write_fixed_point"
> >  GNU gdb (GDB) 11.0.50.20201116-git
> >  ...
> >  Running selftest gdb_mpq_write_fixed_point.
> >  *** stack smashing detected ***: terminated
> >  Aborted (core dumped)
> >  $
> > 
> > I've built a clean gdb from scratch to confirm.
> > 
> > The test passes on Fedora 27, which has libgmp.so.10.3.2:
> > 
> >  $ ./gdb -ex "maint selftest gdb_mpq_write_fixed_point"
> >  GNU gdb (GDB) 11.0.50.20201116-git
> >  Running selftest gdb_mpq_write_fixed_point.
> >  Ran 1 unit tests, 0 failed
> > 
> > Anyone else seeing this?
> > 
> 
> I didn't see it in my -O0 compiled GDB, but I do see it in my -O2 compiled GDB.

Hmmm, I'm wondering if this might be indicative of a bug in GDB,
rather than in GMP. I will take a look at it this weekend.

Thanks Pedro and Simon.

-- 
Joel