unix/mpconfigport_dev.h: Enable recently added optional features.
Specifically, MICROPY_PY_BUILTINS_MEMORYVIEW_ITEMSIZE and
MICROPY_PY_BUILTINS_NEXT2.
#define MICROPY_PY_REVERSE_SPECIAL_METHODS (1)
#define MICROPY_PY_BUILTINS_HELP (1)
#define MICROPY_PY_BUILTINS_HELP_MODULES (1)
+#define MICROPY_PY_BUILTINS_MEMORYVIEW_ITEMSIZE (1)
+#define MICROPY_PY_BUILTINS_NEXT2 (1)
#define MICROPY_PY_BUILTINS_RANGE_BINOP (1)
#define MICROPY_PY_MICROPYTHON_FUNCTION (1)
#define MICROPY_PY_SYS_GETSIZEOF (1)
