mx_leftdiv_conform() API change from 3.4.2 to 3.4.3

[Thomas Weber]

Hi, 

mx_leftdiv_conform() (defined in src/xdvi.cc and exported as public
interface) changed its signature between 3.4.2 and 3.4.3 to fix #33997,
see 
http://hg.savannah.gnu.org/hgweb/octave/rev/f217edac2c71

I think the API number should have been bumped, as well as the soname, 
for that change. Then again, the function seems to be only used
internally in xdiv.cc, so maybe it shouldn't be exported at all?

And related to that: there's also mx_leftdiv_conform() in
src/sparse-xdiv.cc, but that wasn't changed in the above changeset. 
I didn't look at it closely, so maybe it's correct that the fix from
xdiv.cc isn't applied there.

Thanks
        Thomas