Everywhere: void arguments to C functions

Problem:
- C functions with no arguments require a single `void` in the argument list.

Solution:
- Put the `void` in the argument list of functions in C header files.

Libraries/LibC/syslog.cpp

@@ -94,7 +94,7 @@ void closelog_r(struct syslog_data* data)
     data->maskpri = LOG_UPTO(LOG_DEBUG);
 }
 
-void closelog()
+void closelog(void)
 {
     closelog_r(&global_log_data);
 }