Merge pull request #438 from fpistm/friend_declaration

Fix build issue with arm none eabi gcc v9.2.1

Author: soundanalogous

Firmata.h

@@ -128,7 +128,7 @@ class FirmataClass
 
     /* private methods ------------------------------ */
     void strobeBlinkPin(byte pin, int count, int onInterval, int offInterval);
-    friend void FirmataMarshaller::encodeByteStream (size_t bytec, uint8_t * bytev, size_t max_bytes = 0) const;
+    friend void FirmataMarshaller::encodeByteStream (size_t bytec, uint8_t * bytev, size_t max_bytes) const;
 
     /* callback functions */
     static callbackFunction currentAnalogCallback;