[boost] warning about metacomm darwin results

The metacomm darwin results use a toolset named gcc-3.1-darwin. Yet, its corresponding config_info test (http://tinyurl.com/5afdp) reveals that the version of GCC used is 3.3, and not 3.1; this could be misleading. Best, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo