The configure script is actually looking for these packages so that you can try out the SWIG examples contained in the 'Examples' directory without having to hack Makefiles. In addition, a full build of SWIG requires the use of bison. The Examples directory contains a variety of examples of using SWIG and it has some browsable documentation. As this is an unstable development release, the documentation is not quite up to date and is being worked on. We are working on it, but there is a lot of documentation and it is going to take time to complete.
All contributions help.