speedup some node selection operations, this can have a significant impact

* xpath.c: speedup some node selection operations, this can
  have a significant impact on DocBook Norm's stylesheets
* nanohttp.c: someone reported that SOCKLEN_T may not be defined
  make sure it's always the case
* debugXML.c: distinguish CDATA and comments in ls operations
Daniel
diff --git a/nanohttp.c b/nanohttp.c
index 4e08c5b..7acddca 100644
--- a/nanohttp.c
+++ b/nanohttp.c
@@ -78,6 +78,12 @@
 #define SOCKET int
 #endif
 
+#ifndef SOCKLEN_T
+#define SOCKLEN_T unsigned int
+#endif
+#ifndef SOCKET
+#define SOCKET int
+#endif
 
 #ifdef STANDALONE
 #define DEBUG_HTTP