Unbreak build with '-Wstrict-prototypes'

include/wlr/types/wlr_cursor.h

@@ -73,7 +73,7 @@ struct wlr_cursor {
 	void *data;
 };
 
-struct wlr_cursor *wlr_cursor_create();
+struct wlr_cursor *wlr_cursor_create(void);
 
 void wlr_cursor_destroy(struct wlr_cursor *cur);
 

include/wlr/types/wlr_output_layout.h

@@ -47,7 +47,7 @@ struct wlr_output_layout_output {
  * physical space relative to one another, and perform various useful operations
  * on that state.
  */
-struct wlr_output_layout *wlr_output_layout_create();
+struct wlr_output_layout *wlr_output_layout_create(void);
 
 void wlr_output_layout_destroy(struct wlr_output_layout *layout);