objtype: Add special unary methods __pos__, __neg__, __invert__.

Conditional on MICROPY_PY_ALL_SPECIAL_METHODS.

py/objtype.c

@@ -330,9 +330,11 @@ mp_obj_t instance_make_new(mp_obj_t self_in, mp_uint_t n_args, mp_uint_t n_kw, c
 const qstr mp_unary_op_method_name[] = {
     [MP_UNARY_OP_BOOL] = MP_QSTR___bool__,
     [MP_UNARY_OP_LEN] = MP_QSTR___len__,
-    //[MP_UNARY_OP_POSITIVE,
-    //[MP_UNARY_OP_NEGATIVE,
-    //[MP_UNARY_OP_INVERT,
+    #if MICROPY_PY_ALL_SPECIAL_METHODS
+    [MP_UNARY_OP_POSITIVE] = MP_QSTR___pos__,
+    [MP_UNARY_OP_NEGATIVE] = MP_QSTR___neg__,
+    [MP_UNARY_OP_INVERT] = MP_QSTR___invert__,
+    #endif
     [MP_UNARY_OP_NOT] = MP_QSTR_, // don't need to implement this, used to make sure array has full size
 };
 

py/qstrdefs.h

@@ -85,6 +85,9 @@ Q(__truediv__)
 Q(__floordiv__)
 Q(__iadd__)
 Q(__isub__)
+Q(__invert__)
+Q(__neg__)
+Q(__pos__)
 #endif
 
 Q(micropython)