delete obsolete macros (mrb_basic + mrb_object)

Over a year ago is not "soon" anymore. See:
88483fad0036e5cb023940f7c6d18006517fa731
243669308dfd10c8444c2992a883e165b9209941
Merge pull request #2577 from cremno/remove-obsolete-macros

delete obsolete macros (mrb_basic + mrb_object)