Make autoconf-2.66 happy.

This removes more lines than it adds and avoids the following warning;

configure.ac:689: warning: AC_DEFINE_UNQUOTED: `
configure.ac:689:       result=
configure.ac:689:       for i in $status_items; do
configure.ac:689:               result="$result SI_$(echo $i | tr 'a-z' 'A-Z')' is not a valid preprocessor define value