[libxml2] Fix unused-parameter warnings

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 81c01ee9ff1493a92dfb3e679a0d6f45d59622aa
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Sat Jun 17 14:12:53 2017 +0200

    Fix unused-parameter warnings

 example/gjobread.c |    2 +-
 runtest.c          |    3 ++-
 xmlIO.c            |    2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/example/gjobread.c b/example/gjobread.c
index d3f6d57..a435ca4 100644
--- a/example/gjobread.c
+++ b/example/gjobread.c
@@ -177,7 +177,7 @@ typedef struct gjob {
 
 
 static gJobPtr
-parseGjobFile(char *filename) {
+parseGjobFile(char *filename ATTRIBUTE_UNUSED) {
     xmlDocPtr doc;
     gJobPtr ret;
     jobPtr curjob;
diff --git a/runtest.c b/runtest.c
index 03816a8..714de27 100644
--- a/runtest.c
+++ b/runtest.c
@@ -2163,7 +2163,8 @@ static void processNode(FILE *out, xmlTextReaderPtr reader) {
 }
 static int
 streamProcessTest(const char *filename, const char *result, const char *err,
-                  xmlTextReaderPtr reader, const char *rng, int options) {
+                  xmlTextReaderPtr reader, const char *rng,
+                  int options ATTRIBUTE_UNUSED) {
     int ret;
     char *temp = NULL;
     FILE *t = NULL;
diff --git a/xmlIO.c b/xmlIO.c
index 8c6509d..14b3c15 100644
--- a/xmlIO.c
+++ b/xmlIO.c
@@ -1876,7 +1876,7 @@ xmlIOHTTPOpen (const char *filename) {
  */
 
 void *
-xmlIOHTTPOpenW(const char *post_uri, int compression)
+xmlIOHTTPOpenW(const char *post_uri, int compression ATTRIBUTE_UNUSED)
 {
 
     xmlIOHTTPWriteCtxtPtr ctxt = NULL;