Compare string contents, not pointer values.

This bug was introduced in r30334. We want to compare the contents of
the strings, not their addresses. This bug caused host script results to
be printed in arbitrary, perhaps not even well-defined, order.

output.cc

@@ -451,7 +451,7 @@ std::string protect_xml(const std::string s) {
 /* This is a helper function to determine the ordering of the script results
    based on their id. */
 static bool scriptid_lessthan(ScriptResult a, ScriptResult b) {
-  return a.get_id() < b.get_id();
+  return strcmp(a.get_id(), b.get_id()) < 0;
 }
 
 static char *formatScriptOutput(ScriptResult sr) {