This test was disabled with 0a0743f25c since
it fails with octave 7.2.0
The test function horzcat now uses a variable length argument list to fix this.
Before octave 7 it seems to be possible to call a N-argument octave function
with > N arguments without any error. With octave 7 this seems no longer to be
possible which caused the test failure.
Swig types can be used by the operators [a,b] or [a;b] if an octave
overload functions horzcat.m or vertcat.m are added in a @swig_ref
subdirectory.
This requires that is_object() (isobject() for octave >= 4.4) returns
true for swig types which is ensured by the swig octave runtime.