Chances are quite good that the installed makeinfo is sufficient.
So ignore false positives where the makeinfo installed is so new
that it violates the cheesy version grep.

http://bugs.gentoo.org/198182

--- configure
+++ configure
@@ -3573,6 +3573,6 @@
       :
     else
-      MAKEINFO="$MISSING makeinfo"
+      :
     fi
     ;;