libobs: Add support for FreeBSD to gs_window

Enable the X11 specific members in the gs_window struct when on FreeBSD.

libobs/graphics/graphics.h

@@ -426,7 +426,7 @@ struct gs_window {
 	void                    *hwnd;
 #elif defined(__APPLE__)
 	__unsafe_unretained id  view;
-#elif defined(__linux__)
+#elif defined(__linux__) || defined(__FreeBSD__)
 	/* I'm not sure how portable defining id to uint32_t is. */
 	uint32_t id;
 	void* display;