Octave failing to compile (default branch)

[José Abílio Matos]

After updating the code to the latest commit I get this:

config.status: creating liboctave/mk-version-h.sh-tmp
config.status: executing liboctave/mk-version-h.sh commands
  GEN      libinterp/builtin-defun-decls.h
  CXX      libinterp/dldfcn/audiodevinfo_la-audiodevinfo.lo
In file included from /home/jamatos/devel/octave/libinterp/octave-value/ov-
intx.h:42,
                 from /home/jamatos/devel/octave/libinterp/octave-value/ov-
int32.h:45,
                 from /home/jamatos/devel/octave/libinterp/dldfcn/
audiodevinfo.cc:49:
libinterp/corefcn/mxarray.h:58:21: error: ‘mxUNKNOWN_CLASS’ conflicts with a 
previous declaration
   58 |   mxUNKNOWN_CLASS = 0,
      |                     ^
In file included from /home/jamatos/devel/octave/libinterp/octave-value/ov.h:
63,
                 from /home/jamatos/devel/octave/libinterp/corefcn/Cell.h:35,
                 from /home/jamatos/devel/octave/libinterp/dldfcn/
audiodevinfo.cc:43:
libinterp/corefcn/mxtypes.h:58:3: note: previous declaration ‘mxClassID 
mxUNKNOWN_CLASS’
   58 |   mxUNKNOWN_CLASS = 0,
      |   ^~~~~~~~~~~~~~~
In file included from /home/jamatos/devel/octave/libinterp/octave-value/ov-
intx.h:42,
                 from /home/jamatos/devel/octave/libinterp/octave-value/ov-
int32.h:45,
                 from /home/jamatos/devel/octave/libinterp/dldfcn/
audiodevinfo.cc:49:
libinterp/corefcn/mxarray.h:59:3: error: ‘mxCELL_CLASS’ conflicts with a 
previous declaration
   59 |   mxCELL_CLASS,
      |   ^~~~~~~~~~~~

It fails also for other  files.

FWIW I using Fedora 31 (gcc 9.2.1).
-- 
José Matos