Remove outdated //-style commented-out code

This makes the whole code-base have zero changes with clang-format
(v13).

include/randr.h

@@ -50,12 +50,6 @@ void output_init_con(Output *output);
  */
 void init_ws_for_output(Output *output);
 
-/**
- * Initializes the specified output, assigning the specified workspace to it.
- *
- */
-//void initialize_output(xcb_connection_t *conn, Output *output, Workspace *workspace);
-
 /**
  * (Re-)queries the outputs via RandR and stores them in the list of outputs.
  *