Add tests for indexing classdef object with empty "()" (bug #44940). * test/Makefile.am: Add bug-44940/module.mk to build system. * test/bug-44940/module.mk: Include two files below in build system. * test/bug-44940/bug-44940.tst: New test file. * test/bug-44940/class_bug44940.m: New classdef file used for test in bug-44940.tst.

%!test
%! a = class_bug44940 ();
%! b = a;
%! c = a ();
%! a.child = 100;
%! assert (a.child, b.child)
%! assert (a.child, c.child)
%! c.child = 500;
%! assert (a.child, b.child)
%! assert (a.child, c.child)