Fix regression in svg output and simplify viewport handling (bug #44765) * gl2ps-renderer.cc (glps-renderer::draw): remove check for GL2PS_NO_FEEDBACK, it it always true after EndViewport * gl2ps-renderer.h (glps-renderer::draw_axes): call gl2psBegin(End)Viewport for every axes and check for GL2PS_NO_FEEDBACK after each axes. * gl2ps-renderer.h (glps-renderer::draw_axes):remove unnecessary "naxes" attribute

%!test
%! f = foo ();
%! x = [f,f];
%! assert (size (x), [1, 2])
%! assert (class (x), "foo")

%!test
%! f = foo ();
%! x = [f,f];
%! tmp = num2cell (x);
%! assert (iscell (tmp))
%! assert (size (tmp), [1, 2])
%! assert (class (tmp{1}), "foo")
%! assert (class (tmp{2}), "foo")