Fix an error in the progressive DTD parsing code

For https://bugzilla.gnome.org/show_bug.cgi?id=689958
We were looking for the wrong character in the input stream
diff --git a/parser.c b/parser.c
index c7802cf..e719c9f 100644
--- a/parser.c
+++ b/parser.c
@@ -12042,7 +12042,7 @@
     }
     if ((ctxt->progressive == XML_PARSER_DTD) ||
         (ctxt->instate == XML_PARSER_DTD)) {
-        if (memchr(chunk, ']', size) != NULL)
+        if (memchr(chunk, '>', size) != NULL)
             return(1);
         return(0);
     }