With no c++ code there is no point showing CXXFLAGS.
diff --git a/configure.ac b/configure.ac
index 18e5f56..9261597 100644
--- a/configure.ac
+++ b/configure.ac
@@ -262,7 +262,6 @@ echo
echo "Compilation............: make (or gmake)"
echo " CPPFLAGS.............: $CPPFLAGS"
echo " CFLAGS...............: $CFLAGS"
-echo " CXXFLAGS.............: $CXXFLAGS"
echo " LDFLAGS..............: $LDFLAGS"
echo
echo "Installation...........: make install (as root if needed, with 'su' or 'sudo')"