Change digitalPinToPinName() into a first class function

This fixes some issues with the new arduino-cli, since compling a lot of libraries
forces linking them as archives, breaking the inline.

Must be tested in the CI to make sure it dones't break anyhing

Author: facchinm

cores/arduino/pinDefinitions.h

@@ -29,9 +29,7 @@ struct _AnalogPinDescription
 #ifdef __cplusplus__
 extern "C" {
 #endif
-inline PinName digitalPinToPinName(pin_size_t P) {
-	return (P >= PINS_COUNT ? NC : g_APinDescription[P].name);
-};
+PinName digitalPinToPinName(pin_size_t P);
 #ifdef __cplusplus__
 }
 #endif

cores/arduino/pinToIndex.cpp

@@ -9,3 +9,13 @@ int PinNameToIndex(PinName P) {
   }
   return NOT_A_PIN;
 }
+
+#ifdef __cplusplus__
+extern "C" {
+#endif
+PinName digitalPinToPinName(pin_size_t P) {
+  return (P >= PINS_COUNT ? NC : g_APinDescription[P].name);
+};
+#ifdef __cplusplus__
+}
+#endif