keep arduino incompatible BUILTIN_LED

Author: tuxedo0801

variants/d1/pins_arduino.h

@@ -43,6 +43,7 @@ static const uint8_t MISO  = 12;
 static const uint8_t SCK   = 14;
 
 static const uint8_t LED_BUILTIN = 2;//new ESP-12E GPIO2
+static const uint8_t BUILTIN_LED = 2;//new ESP-12E GPIO2
 
 static const uint8_t A0 = 17;