If the installed version of Happy is < 1.3, use the one from the tree.
dnl ** check for installed happy binary + version
#
AC_HAPPY
dnl ** check for installed happy binary + version
#
AC_HAPPY
+if expr $HappyVersion \< "1.3" >/dev/null; then
+ echo " Happy Version 1.3 or later is required to compile GHC."
+ echo " Using the Happy sources in the tree.";
+ HappyCmd=""
+fi;