title: Change GCC version used by bjam
body: <p>I am trying to build a library (luabind) with bjam. I came across an error and it seems like the problem is that I need to compile with gcc 4.2, but the default on this computer (Mac OSX) is 4.0. I would prefer not to go around changing links in system directories, is there a way to specify to bjam to use gcc4.2 rather than just gcc?</p>