configure.ac: Strip unused variables from summary
configure.ac: Strip unused variables from summary

Issue #69.

ChrisCummins/chriscummins.github.io,ChrisCummins/chriscummins.github.io,ChrisCummins/chriscummins.cc,ChrisCummins/chriscummins.github.io,ChrisCummins/chriscummins.cc,ChrisCummins/chriscummins.github.io,ChrisCummins/chriscummins.cc,ChrisCummins/chriscummins.github.io