fixing bug #104646 about iconv based encoding conversion when the input

* encoding.c xmlIO.c: fixing bug #104646 about iconv based
  encoding conversion when the input buffer stops in the
  middle of a multibyte char
Daniel
diff --git a/xmlIO.c b/xmlIO.c
index cbc542c..5f28849 100644
--- a/xmlIO.c
+++ b/xmlIO.c
@@ -2364,7 +2364,7 @@
 	     * convert as much as possible to the parser reading buffer.
 	     */
 	    ret = xmlCharEncOutFunc(out->encoder, out->conv, out->buffer);
-	    if (ret < 0) {
+	    if ((ret < 0) && (ret != -3)) {
 		xmlGenericError(xmlGenericErrorContext,
 			"xmlOutputBufferWrite: encoder error\n");
 		return(-1);