more cppcheck warnings fixes

src/concurrency/LockGuard.h

@@ -10,7 +10,7 @@ namespace concurrency {
 class LockGuard
 {
   public:
-    LockGuard(Lock *lock);
+    explicit LockGuard(Lock *lock);
     ~LockGuard();
 
     LockGuard(const LockGuard &) = delete;

src/concurrency/NotifiedWorkerThread.h

@@ -39,7 +39,7 @@ class NotifiedWorkerThread : public OSThread
     virtual void onNotify(uint32_t notification) = 0;
 
     /// just calls checkNotification()
-    virtual int32_t runOnce();
+    virtual int32_t runOnce() override;
 
     /// Sometimes we might want to check notifications independently of when our thread was getting woken up (i.e. if we are about to change
     /// radio transmit/receive modes we want to handle any pending interrupts first).  You can call this method and if any notifications are currently

src/concurrency/Periodic.h

@@ -18,7 +18,7 @@ class Periodic : public OSThread
     Periodic(const char *name, int32_t (*_callback)()) : OSThread(name), callback(_callback) {}
 
   protected:
-    int32_t runOnce() { return callback(); }
+    int32_t runOnce() override { return callback(); }
 };
 
 } // namespace concurrency