libcamera: Drop unneeded empty default constructors and destructors

A few default constructors and destructors are needlessly defined as
empty. Drop them.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <email@uajain.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/signal.h

@@ -38,7 +38,6 @@ template<typename... Args>
 class Signal : public SignalBase
 {
 public:
-	Signal() {}
 	~Signal()
 	{
 		disconnect();

test/media_device/media_device_print_test.cpp

@@ -25,10 +25,6 @@ using namespace std;
  */
 class MediaDevicePrintTest : public Test
 {
-public:
-	MediaDevicePrintTest() {}
-	~MediaDevicePrintTest() {}
-
 protected:
 	int init() { return 0; }
 	int run();