[libxml2] Fixup for buf.c

[Daniel Veillard <veillard src gnome org>]

commit 6f6feba876eeff3a75fc10cdc2f414cc66204dde
Author: Daniel Veillard <veillard redhat com>
Date:   Wed Jul 25 16:30:56 2012 +0800

    Fixup for buf.c

 buf.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/buf.c b/buf.c
index c2123aa..7e293e6 100644
--- a/buf.c
+++ b/buf.c
@@ -1141,11 +1141,12 @@ xmlBufBackToBuffer(xmlBufPtr buf) {
  */
 int
 xmlBufMergeBuffer(xmlBufPtr buf, xmlBufferPtr buffer) {
-    int ret;
+    int ret = 0;
 
     if ((buf == NULL) || (buf->error))
-        return(0);
-    if ((buf != NULL) && (buffer->content != NULL) && (buffer->use > 0)) {
+        ret = -1;
+    else if ((buffer != NULL) && (buffer->content != NULL) &&
+             (buffer->use > 0)) {
         ret = xmlBufAdd(buf, buffer->content, buffer->use);
     }
     xmlBufferFree(buffer);