Echo CC, CXX and CPP at the end of configure

configure.ac

@@ -659,6 +659,9 @@ echo "Build:          $build"
 echo "Host:           $host"
 echo "Target:         $target"
 echo "Install prefix: $prefix"
+echo "CC:             $CC"
+echo "CXX:            $CXX"
+echo "CPP:            $CPP"
 echo "CXXFLAGS:       $CXXFLAGS"
 echo "CFLAGS:         $CFLAGS"
 echo "CPPFLAGS:       $CPPFLAGS"