Added a destroy virtual method to all source input plugin main classes

plugins/samplesource/filesource/filesourceinput.cpp

@@ -91,6 +91,11 @@ FileSourceInput::~FileSourceInput()
 	stop();
 }
 
+void FileSourceInput::destroy()
+{
+    delete this;
+}
+
 void FileSourceInput::openFileStream()
 {
 	//stopInput();

plugins/samplesource/filesource/filesourceinput.h

@@ -212,6 +212,7 @@ public:
 
 	FileSourceInput(DeviceSourceAPI *deviceAPI);
 	virtual ~FileSourceInput();
+	virtual void destroy();
 
 	virtual bool start();
 	virtual void stop();