Windows: MSVC2017: fixed some attribute unused cases

devices/hackrf/devicehackrf.h

@@ -30,11 +30,7 @@ public:
 protected:
     DeviceHackRF();
     DeviceHackRF(const DeviceHackRF&) {}
-#ifdef _MSC_VER
-    DeviceHackRF& operator=(const DeviceHackRF& other) { return *this; }
-#else
-    DeviceHackRF& operator=(const DeviceHackRF& other __attribute__((unused))) { return *this; }
-#endif
+    DeviceHackRF& operator=(const DeviceHackRF& other) { (void) other; return *this; }
     ~DeviceHackRF();
 private:
     static hackrf_device *open_hackrf_from_sequence(int sequence);

sdrgui/soapygui/arginfogui.cpp

@@ -363,12 +363,9 @@ void ArgInfoGUI::on_argEdit_editingFinished()
     emit valueChanged();
 }
 
-#ifdef _MSC_VER
 void ArgInfoGUI::on_argCombo_currentIndexChanged(int index)
-#else
-void ArgInfoGUI::on_argCombo_currentIndexChanged(int index __attribute__((unused)))
-#endif
 {
+    (void) index;
     QVariant v = ui->argCombo->currentData();
     bool ok = false;