configure.ac: Add optional third variable to results.

Add optional third value to results() to allow for non "yes" answers which are
considered positive.

m4/pretty_print.m4

@@ -1,17 +1,19 @@
 AC_DEFUN([results], [
 	dnl This is a hack to allow "with" names, otherwise "enable".
-	num=`expr match $1 "with"`
+	num=`expr match $1 'with'`
 	if test "$num" != "0"; then
 		var="`echo '$'$1`"
 	else
 		var="`echo '$'enable_$1`"
 	fi
 
-	echo -n "("
+	echo -n '('
 	if eval "test x$var = xyes"; then
-		echo -n "+"
+		echo -n '+'
+	elif test -n "$3" && eval "test x$var = x$3"; then
+		echo -n '+' 
 	else
-		echo -n "-"
+		echo -n '-'
 	fi
 	echo -n "$2) "
 ])