Test for --enable-xml.

Author: Andrei Zmievski

ext/wddx/config.m4

@@ -5,8 +5,8 @@ AC_MSG_CHECKING(whether to include WDDX support)
 AC_ARG_WITH(wddx,
 [  --with-wddx             Include WDDX support],[
   if test "$withval" = "yes"; then
-    if test "${with_xml+set}" != "set" -o "$with_xml" = "no"; then
-	AC_MSG_ERROR(WDDX requires --with-xml)
+    if test "${enable_xml+set}" != "set" -o "$enable_xml" = "no"; then
+	AC_MSG_ERROR(WDDX requires --enable-xml)
     else
         AC_DEFINE(HAVE_WDDX, 1, [ ])
         AC_MSG_RESULT(yes)