Split log_{input,output} into log_{stdin,ttyin} and log_{ttyout,stdout,stderr}

If log_input is set, log_{stdin,ttyin} will be set as well.
If log_output is set, log_{stdout,stderr,ttyout} will be set as well.
This provides more fine-grained control over I/O logging and makes it
possible to disable logging piped or redirected intput or output.

plugins/sudoers/audit.c

@@ -261,7 +261,7 @@ log_server_accept(struct eventlog *evlog)
 	    debug_return_bool(true);
     } else {
 	/* Only send accept event to log server if I/O log plugin did not. */
-	if (def_log_input || def_log_output)
+	if (iolog_enabled)
 	    debug_return_bool(true);
     }