Replace NULL by nullptr in C++ include files

Author: GrumpyOldPizza

cores/arduino/Callback.h

@@ -61,7 +61,7 @@ class Callback {
     bool queue();
     void call();
 
-    operator bool() { return (_callback != NULL); }
+    operator bool() { return (_callback != nullptr); }
 
 private:
     void (*_callback)(void*);

cores/arduino/FS.h

@@ -120,7 +120,7 @@ class DirEntry
 
     DirEntry() { _info.type = DT_UNKNOWN; }
 
-    const char *name() { return (_info.type == DT_UNKNOWN) ? NULL : _info.name; }
+    const char *name() { return (_info.type == DT_UNKNOWN) ? nullptr : _info.name; }
     size_t fileSize() { return (_info.type == DT_UNKNOWN) ? 0 : _info.size; };
     bool isDirectory() { return _info.type == DT_DIR; }
     bool isFile() { return _info.type == DT_REG; }

libraries/LoRaWAN/src/LoRaWAN.h

@@ -116,7 +116,7 @@ class LoRaWANClass : public Stream
     int begin(const struct LoRaWANBand &band);
 
     int joinOTAA();
-    int joinOTAA(const char *appEui, const char *appKey, const char *devEui = NULL);
+    int joinOTAA(const char *appEui, const char *appKey, const char *devEui = nullptr);
     int rejoinOTAA();
 
     int joinABP();