small cleanup switched DTD validation to use only regexp when configured

* HTMLparser.c: small cleanup
* valid.c xmlregexp.c: switched DTD validation to use only regexp
  when configured with them. A bit of debugging around the determinism
  checks is still needed
Daniel
diff --git a/xmlregexp.c b/xmlregexp.c
index d613d4c..8ff7385 100644
--- a/xmlregexp.c
+++ b/xmlregexp.c
@@ -161,6 +161,7 @@
     int max;
 
     void *valuep;
+    void *valuep2;
     int neg;
     int codepoint;
     xmlRegStatePtr start;