Fix MacOSX compile error

screen_capture/linux/screen_capture_wgc.cpp

@@ -0,0 +1,26 @@
+#include "screen_capture_wgc.h"
+
+#include <iostream>
+
+ScreenCaptureWgc::ScreenCaptureWgc() {}
+
+ScreenCaptureWgc::~ScreenCaptureWgc() {}
+
+bool ScreenCaptureWgc::IsWgcSupported() { return false; }
+
+int ScreenCaptureWgc::Init(const RECORD_DESKTOP_RECT &rect, const int fps,
+                           cb_desktop_data cb) {
+  return 0;
+}
+
+int ScreenCaptureWgc::Start() { return 0; }
+
+int ScreenCaptureWgc::Pause() { return 0; }
+
+int ScreenCaptureWgc::Resume() { return 0; }
+
+int ScreenCaptureWgc::Stop() { return 0; }
+
+void ScreenCaptureWgc::OnFrame() {}
+
+void ScreenCaptureWgc::CleanUp() {}