more fixes and extending the tests coverage more hardeing of APIs skip

* gentest.py testapi.c: more fixes and extending the tests coverage
* xmlwriter.c list.c: more hardeing of APIs
* doc/apibuild.py: skip testapi.c when scanning the C files.
Daniel
diff --git a/doc/apibuild.py b/doc/apibuild.py
index 059d0bb..2cbf32f 100755
--- a/doc/apibuild.py
+++ b/doc/apibuild.py
@@ -32,6 +32,7 @@
   "rngparser.c": "not yet integrated",
   "rngparser.h": "not yet integrated",
   "elfgcchack.h": "not a normal header",
+  "testapi.c": "generated regression tests",
 }
 
 ignored_words = {