ports: Enable descriptors on stm32, esp8266, esp32 ports.

dpgeorge · dpgeorge · commit 93150a0d40a6 · 2018-06-08T12:23:08.000+10:00
They are now efficient (in runtime performance) and provide a useful feature that's hard to obtain without them enabled. See issue adafruit#3644 and PR adafruit#3826 for background.
diff --git a/ports/esp32/mpconfigport.h b/ports/esp32/mpconfigport.h
@@ -57,6 +57,7 @@
 
 // control over Python builtins
 #define MICROPY_PY_FUNCTION_ATTRS           (1)
+#define MICROPY_PY_DESCRIPTORS              (1)
 #define MICROPY_PY_STR_BYTES_CMP_WARN       (1)
 #define MICROPY_PY_BUILTINS_STR_UNICODE     (1)
 #define MICROPY_PY_BUILTINS_STR_CENTER      (1)
diff --git a/ports/esp8266/mpconfigport.h b/ports/esp8266/mpconfigport.h
@@ -30,6 +30,7 @@
 #define MICROPY_CAN_OVERRIDE_BUILTINS (1)
 #define MICROPY_USE_INTERNAL_ERRNO  (1)
 #define MICROPY_ENABLE_SCHEDULER    (1)
+#define MICROPY_PY_DESCRIPTORS      (1)
 #define MICROPY_PY_ALL_SPECIAL_METHODS (1)
 #define MICROPY_PY_BUILTINS_COMPLEX (0)
 #define MICROPY_PY_BUILTINS_STR_UNICODE (1)
diff --git a/ports/stm32/mpconfigport.h b/ports/stm32/mpconfigport.h
@@ -82,6 +82,7 @@
 
 // control over Python builtins
 #define MICROPY_PY_FUNCTION_ATTRS   (1)
+#define MICROPY_PY_DESCRIPTORS      (1)
 #define MICROPY_PY_BUILTINS_STR_UNICODE (1)
 #define MICROPY_PY_BUILTINS_STR_CENTER (1)
 #define MICROPY_PY_BUILTINS_STR_PARTITION (1)
