Make bintest enabling like other `enable_xxx` methods.
Merge pull request #2032 from take-cheeze/enable_bintest

Make bintest enabling like other `enable_xxx` methods.
Add MRB_TT_HAS_BASIC_P macro to check whether a typetag has MRB_OBJECT_HEADER.
Merge pull request #2033 from take-cheeze/mrb_tt_has_basic_p

Add MRB_TT_HAS_BASIC_P macro.