Fix a bunch of scan 'dead increments' and cleanup

* HTMLparser.c c14n.c debugXML.c entities.c nanohttp.c parser.c
  testC14N.c uri.c xmlcatalog.c xmllint.c xmlregexp.c xpath.c:
  fix unused variables, or unneeded increments as well as a couple
  of space issues
* runtest.c: check for NULL before calling unlink()
diff --git a/xpath.c b/xpath.c
index a1b7dda..ab130d3 100644
--- a/xpath.c
+++ b/xpath.c
@@ -14505,7 +14505,7 @@
 		    namespaces[i++] = ns->prefix;
 		}
 		namespaces[i++] = NULL;
-		namespaces[i++] = NULL;
+		namespaces[i] = NULL;
 	    }
 	}