Rename operator TEST_EMPTY into EMPTY_P to be compliant with iterator operator

m-variant.h

@@ -741,7 +741,7 @@
    CLEAR(M_C(name, _clear)),                                                  \
    CLEAN(M_C(name, _clean)),                                                  \
    TYPE(M_C(name,_ct)),                                                       \
-   TEST_EMPTY(M_C(name,_empty_p)),                                            \
+   EMPTY_P(M_C(name,_empty_p)),                                               \
    M_IF_METHOD_ALL(HASH, __VA_ARGS__)(HASH(M_C(name, _hash)),),               \
    M_IF_METHOD_ALL(EQUAL, __VA_ARGS__)(EQUAL(M_C(name, _equal_p)),),          \
    M_IF_METHOD_ALL(GET_STR, __VA_ARGS__)(GET_STR(M_C(name, _get_str)),),      \