nanohttp: Deprecate public API

The long-term plan is to remove the built-in HTTP client. There are
still a few downstream projects that use libxml2's client for other
purposes. These users should get deprecation warnings now.

python/generator.py

@@ -319,6 +319,9 @@ deprecated_funcs = {
     'xmlNanoFTPInit': True,
     'xmlNanoFTPProxy': True,
     'xmlNanoFTPScanProxy': True,
+    'xmlNanoHTTPCleanup': True,
+    'xmlNanoHTTPInit': True,
+    'xmlNanoHTTPScanProxy': True,
     'xmlNewGlobalNs': True,
     'xmlNextChar': True,
     'xmlParseAttValue': True,