Okay this is scary but it is just adding a configure option to disable

* HTMLtree.c SAX2.c c14n.c catalog.c configure.in debugXML.c
  encoding.c entities.c nanoftp.c nanohttp.c parser.c relaxng.c
  testAutomata.c testC14N.c testHTML.c testRegexp.c testRelax.c
  testSchemas.c testXPath.c threads.c tree.c valid.c xmlIO.c
  xmlcatalog.c xmllint.c xmlmemory.c xmlreader.c xmlschemas.c
  example/gjobread.c include/libxml/HTMLtree.h include/libxml/c14n.h
  include/libxml/catalog.h include/libxml/debugXML.h
  include/libxml/entities.h include/libxml/nanohttp.h
  include/libxml/relaxng.h include/libxml/tree.h
  include/libxml/valid.h include/libxml/xmlIO.h
  include/libxml/xmlschemas.h include/libxml/xmlversion.h.in
  include/libxml/xpathInternals.h python/libxml.c:
  Okay this is scary but it is just adding a configure option
  to disable output, this touches most of the files.
Daniel
diff --git a/testC14N.c b/testC14N.c
index bdacc22..6a36a68 100644
--- a/testC14N.c
+++ b/testC14N.c
@@ -7,7 +7,7 @@
  * Author: Aleksey Sanin <aleksey@aleksey.com>
  */
 #include "libxml.h"
-#if defined(LIBXML_C14N_ENABLED)
+#if defined(LIBXML_C14N_ENABLED) && defined(LIBXML_OUTPUT_ENABLED)
 
 #include <stdio.h>
 #include <string.h>
@@ -348,8 +348,8 @@
 
 #else
 #include <stdio.h>
-int main(int argc, char **argv) {
-    printf("%s : XPath/Canonicalization support not compiled in\n", argv[0]);
+int main(int argc ATTRIBUTE_UNUSED, char **argv ATTRIBUTE_UNUSED) {
+    printf("%s : XPath/Canonicalization and output support not compiled in\n", argv[0]);
     return(0);
 }
 #endif /* LIBXML_C14N_ENABLED */