Logging: add argument --log-show-basename

Optionally strips leading path from filenames when logging.

intern/clog/CLG_log.h

@@ -144,6 +144,7 @@ void CLG_init(void);
 void CLG_exit(void);
 
 void CLG_output_set(void *file_handle);
+void CLG_output_use_basename_set(bool value);
 void CLG_fatal_fn_set(void (*fatal_fn)(void *file_handle));
 
 void CLG_type_filter_include(const char *type_filter, int type_filter_len);